Novel sulfonyldiazomethanes, photoacid generators, resist compositions, and patterning process

ABSTRACT

A chemical amplification type resist composition comprising a specific benzenesulfonyldiazomethane containing a long-chain alkoxyl group at the 2-position on benzene ring has many advantages including improved resolution, improved focus latitude, minimized line width variation or shape degradation even on long-term PED, minimized debris left after coating, development and peeling, and improved pattern profile after development and is thus suited for microfabrication.

[0001] This invention relates to novel sulfonyldiazomethane compounds,photoacid generators for resist compositions, resist compositionscomprising the photoacid generators, and a patterning process using thesame. The resist compositions, especially chemical amplification typeresist compositions are sensitive to such radiation as UV, deep UV,electron beams, x-rays, excimer laser beams, γ-rays, and synchrotronradiation and suitable for the microfabrication of integrated circuits.

BACKGROUND OF THE INVENTION

[0002] While a number of efforts are currently being made to achieve afiner pattern rule in the drive for higher integration and operatingspeeds in LSI devices, deep-ultraviolet lithography is thought to holdparticular promise as the next generation in microfabricationtechnology.

[0003] One technology that has attracted a good deal of attentionrecently utilizes as the deep UV light source a high-intensity KrFexcimer laser, especially an ArF excimer laser featuring a shorterwavelength. There is a desire to have a microfabrication technique offiner definition by combining exposure light of shorter wavelength witha resist material having a higher resolution.

[0004] In this regard, the recently developed, acid-catalyzed, chemicalamplification type resist materials are expected to comply with the deepUV lithography because of their many advantages including highsensitivity, resolution and dry etching resistance. The chemicalamplification type resist materials include positive working materialsthat leave the unexposed areas with the exposed areas removed andnegative working materials that leave the exposed areas with theunexposed areas removed.

[0005] In chemical amplification type, positive working, resistcompositions to be developed with alkaline developers, an alkali-solublephenol or a resin and/or compound in which carboxylic acid is partiallyor entirely protected with acid-labile protective groups (acid labilegroups) is catalytically decomposed by an acid which is generated uponexposure, to thereby generate the phenol or carboxylic acid in theexposed area which is removed by an alkaline developer. Also, in similarnegative working resist compositions, an alkali-soluble phenol or aresin and/or compound having carboxylic acid and a compound(crosslinking agent) capable of bonding or crosslinking the resin orcompound under the action of an acid are crosslinked with an acid whichis generated upon exposure whereby the exposed area is converted to beinsoluble in an alkaline developer and the unexposed area is removed bythe alkaline developer.

[0006] On use of the chemical amplification type, positive working,resist compositions, a resist film is formed by dissolving a resinhaving acid labile groups as a binder and a compound capable ofgenerating an acid upon exposure to radiation (to be referred to asphotoacid generator) in a solvent, applying the resist solution onto asubstrate by a variety of methods, and evaporating off the solventoptionally by heating. The resist film is then exposed to radiation, forexample, deep UV through a mask of a predetermined pattern. This isoptionally followed by post-exposure baking (PEB) for promotingacid-catalyzed reaction. The exposed resist film is developed with anaqueous alkaline developer for removing the exposed area of the resistfilm, obtaining a positive pattern profile. The substrate is then etchedby any desired technique. Finally the remaining resist film is removedby dissolution in a remover solution or ashing, leaving the substratehaving the desired pattern profile.

[0007] The chemical amplification type, positive working, resistcompositions adapted for KrF excimer lasers generally use a phenolicresin, for example, polyhydroxystyrene in which some or all of thehydrogen atoms of phenolic hydroxyl groups are protected with acidlabile protective groups. Iodonium salts, sulfonium salts, andbissulfonyldiazomethane compounds are typically used as the photoacidgenerator. If necessary, there are added additives, for example, adissolution inhibiting or promoting compound in the form of a carboxylicacid and/or phenol derivative having a molecular weight of up to 3,000in which some or all of the hydrogen atoms of carboxylic acid and/orphenolic hydroxyl groups are protected with acid labile groups, acarboxylic acid compound for improving dissolution characteristics, abasic compound for improving contrast, and a surfactant for improvingcoating characteristics.

[0008] Bissulfonyldiazomethanes as shown below are advantageously usedas the photoacid generator in chemical amplification type resistcompositions, especially chemical amplification type, positive working,resist compositions adapted for KrF excimer lasers because they providea high sensitivity and resolution and eliminate poor compatibility withresins and poor solubility in resist solvents as found with thesulfonium and iodonium salt photoacid generators.

[0009] Although these photoacid generators are highly lipophilic andhighly soluble in resist solvents, they have poor affinity to orsolubility in developers so that upon development and/or resist removal,the photoacid generators can be left on the substrate as insolublematter (consisting of the photoacid generator or a mixture thereof withthe resin).

[0010] For example, upon development, the resist material which has pooraffinity to or solubility in a developer deposits on developed spaces inthe exposed area or on lines in the unexposed area as foreign matter.

[0011] JP-A 3-103854 discloses bis(4-methoxyphenylsulfonyl)diazomethaneas a photoacid generator having a methoxy group introduced therein. Aslong as we confirmed, the methoxy group is not fully effective. Thephotoacid generator is often left on the substrate as insoluble matter(consisting of the photoacid generator or a mixture thereof with theresin) upon development and/or resist film removal.

[0012] If unsubstituted bis(phenylsulfonyl)diazomethane orbis(cyclohexylsulfonyl)diazomethane having alkyl groups instead of arylgroups is used in a resist material as the photoacid generator forreducing lipophilic property, resolution is deteriorated. If it is addedin large amounts, the problem of insoluble matter upon developmentand/or resist film removal remains unsolved.

[0013] Aside from the countermeasure for foreign matter, JP-A 10-90884discloses to introduce such an acid labile group as t-butoxycarbonyloxy,ethoxyethyl or tetrahydropyranyl into disulfonediazomethane for thepurpose of improving the contrast of positive resist material. Weempirically found that these compounds are unstable and ineffective foreliminating the foreign matter upon development and resist film removal.

[0014] Searching for a countermeasure to the foreign matter problem, wealready synthesized sulfonyldiazomethanes having an acyl group (e.g.,acetyl) or methanesulfonyl group introduced therein and found that theywere useful as the photoacid generator in chemical amplification typeresist composition. Since these arylsulfonyldiazomethanes having an acylgroup or methanesulfonyl group introduced therein lack stability underbasic conditions during their synthesis, the yield of diazo formation issometimes low. See JP-A 2001-055373 and JP-A 2001-106669.

[0015] It is known from JP-A 8-123032 to use two or more photoacidgenerators in a resist material. JP-A 11-72921 discloses the use of aradiation-sensitive acid generator comprising in admixture a compoundwhich generates a sulfonic acid having at least three fluorine atomsupon exposure to radiation and a compound which generates a fluorineatom-free sulfonic acid upon exposure to radiation, thereby improvingresolution without inviting nano-edge roughness and film surfaceroughening. JP-A 11-38604 describes that a resist composition comprisingan asymmetric bissulfonyldiazomethane such as a bissulfonyldiazomethanehaving alkylsulfonyl and arylsulfonyl groups or abissulfonyldiazomethane having arylsulfonyl and alkoxy-substitutedarylsulfonyl groups and a polyhydroxystyrene derivative having acidlabile groups as the polymer has a resolution at least comparable toprior art compositions, a sufficient sensitivity and significantlyimproved heat resistance. However, we empirically found that theseresist compositions are unsatisfactory in resolution and in the effectof eliminating the foreign matter on the pattern upon development. Fromthe synthetic and industrial standpoints, it is difficult to obtainbilaterally asymmetric bissulfonyldiazomethanes.

[0016] Aside from the above-discussed problem of insoluble matter upondevelopment and/or removal, there is also a problem that the patternprofile often changes when the period from exposure to post-exposurebaking (PEB) is prolonged, which is known as post-exposure delay (PED).Such changes frequently reveal as a slimming of the line width ofunexposed areas in the case of chemical amplification type positiveresist compositions using acetal and analogous acid labile groups, andas a thickening of the line width of unexposed areas in the case ofchemical amplification type positive resist compositions usingtert-butoxycarbonyl (t-BOC) and analogous acid labile groups. Since theperiod from exposure to PEB is often prolonged for the operationalreason, there is a desire to have a stable resist composition which isfree from such changes, that is, has PED stability.

[0017] In some resist processes, baking is performed at far highertemperatures (e.g., 130° C.) than the customary baking temperature of120° C. or below as disclosed in JP-A 6-266112. In this case, thebissulfonyldiazomethanes shown above by structural formulae can bethermally decomposed to generate acids due to their low heat resistanceso that acidolysis takes place everywhere regardless of whether theareas are exposed or unexposed, failing in pattern formation.

[0018] The solubility of photosensitive agents or photoacid generatorswas the problem from the age when quinonediazide photosensitive agentswere used in non-chemical amplification type resist materials. Specificconsiderations include the solubility of photoacid generators in resistsolvents, the compatibility of photoacid generators with resins, thesolubility (or affinity) of photo-decomposed products after exposure andPEB and non-decomposed compound (photoacid generator) in a developer,and the solubility of the photoacid generator and photo-decomposedproducts thereof in a remover solvent upon resist removal or peeling. Ifthese factors are poor, there can occur problems including precipitationof the photoacid generator during storage, difficulty of filtration,uneven coating, striation, abnormal resist sensitivity, and foreignmatter, left-over and staining on the pattern and in spaces afterdevelopment.

[0019] The photoacid generator in resist material is required to meet afully high solubility in (or compatibility with) a resist solvent and aresin, good storage stability, non-toxicity, effective coating, awell-defined pattern profile, PED stability, no foreign matter leftduring pattern formation after development and upon resist removal, andheat resistance. The conventional photoacid generators, especiallydiazodisulfone photoacid generators do not meet all of theserequirements.

[0020] As the pattern of integrated circuits becomes finer in thesedays, a higher resolution is, of course, required, and the problem offoreign matter after development and resist removal becomes moreserious.

SUMMARY OF THE INVENTION

[0021] An object of the invention is to provide a novelsulfonyldiazomethane for use in a resist composition, especially of thechemical amplification type, such that the resist composition minimizesthe foreign matter left after coating, development and resist removal,has satisfactory heat resistance, and ensures a well-defined patternprofile after development. Another object of the invention is to providea photoacid generator for resist compositions, a resist compositioncomprising the photoacid generator, and a patterning process using thesame.

[0022] We have found that by using a sulfonyldiazomethane compound ofthe general formula (1), especially formula (1a), to be defined below,as the photoacid generator in a resist composition, there are achieved anumber of advantages including dissolution, storage stability, effectivecoating, minimized line width variation or shape degradation duringlong-term PED, minimized foreign matter left after coating, developmentand resist removal, satisfactory heat resistance, a well-defined patternprofile after development, and a high resolution enough formicrofabrication, especially by deep UV lithography. Better results areobtained when a sulfonyldiazomethane compound of the formula (1),especially formula (1a), is used as the photoacid generator in achemical amplification type resist composition, typically chemicalamplification positive type resist composition comprising a resin whichchanges its solubility in an alkaline developer under the action of anacid as a result of scission of C—O—C linkages. The composition exertsits effect to the maximum extent when processed by deep UV lithography.

[0023] In a first aspect, the invention provides a sulfonyldiazomethanecompound having the following general formula (1).

[0024] Herein R is each independently a substituted or unsubstitutedstraight, branched or cyclic alkyl group of 1 to 4 carbon atoms, G isSO₂ or CO, R³ is a substituted or unsubstituted straight, branched orcyclic alkyl group of 1 to 10 carbon atoms or a substituted orunsubstituted aryl group of 6 to 14 carbon atoms, p is 1 or 2, q is 0 or1, satisfying p+q=2, m is an integer of 3 to 11, and k is an integer of0 to 4, with the proviso that in the event k is at least 1, at least oneof R associated with k may bond with the R at the 4-position to form acyclic structure with the carbon atoms on the benzene ring to whichthese R's are attached, and then, these two R's bond together to form analkylene group of 3 to 4 carbon atoms.

[0025] Typical sulfonyldiazomethane compounds have the following generalformula (1a).

[0026] wherein R is each independently a substituted or unsubstitutedstraight, branched or cyclic alkyl group of 1 to 4 carbon atoms, and mis an integer of 3 to 11.

[0027] In a second aspect, the invention provides a photoacid generatorfor a chemical amplification type resist composition comprising thesulfonyldiazomethane compound of formula (1) or (1a).

[0028] In a third aspect, the invention provides a chemicalamplification type resist composition comprising (A) a resin whichchanges its solubility in an alkaline developer under the action of anacid, (B) the sulfonyldiazomethane compound of formula (1) or (1a) whichgenerates an acid upon exposure to radiation, and optionally, (C) acompound capable of generating an acid upon exposure to radiation, otherthan component (B). The resist composition may further contain (D) abasic compound, (E) an organic acid derivative, and an organic solvent.

[0029] The resin (A) typically has such substituent groups having C—O—Clinkages that the solubility in an alkaline developer changes as aresult of scission of the C—O—C linkages under the action of an acid.

[0030] In a preferred embodiment, the resin (A) is a polymer containingphenolic hydroxyl groups in which hydrogen atoms of the phenolichydroxyl groups are substituted with acid labile groups of one or moretypes in a proportion of more than 0 mol % to 80 mol % on the average ofthe entire hydrogen atoms of the phenolic hydroxyl groups, the polymerhaving a weight average molecular weight of 3,000 to 100,000.

[0031] More preferably, the resin (A) is a polymer comprising recurringunits of the following general formula (2a):

[0032] wherein R⁴ is hydrogen or methyl, R⁵ is a straight, branched orcyclic alkyl group of 1 to 8 carbon atoms, x is 0 or a positive integer,y is a positive integer, satisfying x+y≦5, R⁶ is an acid labile group, Sand T are positive integers, satisfying 0<T/(S+T)≦0.8, wherein thepolymer contains units in which hydrogen atoms of phenolic hydroxylgroups are partially substituted with acid labile groups of one or moretypes, a proportion of the acid labile group-bearing units is on theaverage from more than 0 mol % to 80 mol % based on the entire polymer,and the polymer has a weight average molecular weight of 3,000 to100,000.

[0033] In another preferred embodiment, the resin (A) is a polymercomprising recurring units of the following general formula (2a′):

[0034] wherein R⁴ is hydrogen or methyl, R⁵ is a straight, branched orcyclic alkyl group of 1 to 8 carbon atoms, R⁶ is an acid labile group,R^(6a) is hydrogen or an acid labile group, at least some of R^(6a)being acid labile groups, x is 0 or a positive integer, y is a positiveinteger, satisfying x+y≦5, M and N are positive integers, L is 0 or apositive integer, satisfying 0<N/(M+N+L)≦0.5 and 0<(N+L)/(M+N+L)≦0.8,wherein the polymer contains on the average from more than 0 mol % to 50mol % of those units derived from acrylate and methacrylate, and alsocontains on the average from more than 0 mol % to 80 mol % of acidlabile group-bearing units, based on the entire polymer, and the polymerhas a weight average molecular weight of 3,000 to 100,000.

[0035] In a further preferred embodiment, the resin (A) is a polymercomprising recurring units of the following general formula (2a″):

[0036] wherein R⁴ is hydrogen or methyl, R⁵ is a straight, branched orcyclic alkyl group of 1 to 8 carbon atoms, R⁶ is an acid labile group,R^(6a) is hydrogen or an acid labile group, at least some of R^(6a)being acid labile groups, x is 0 or a positive integer, y is a positiveinteger, satisfying x+y≦5, yy is 0 or a positive integer, satisfyingx+yy≦5, A and B are positive integers, C, D and E each are 0 or apositive integer, satisfying 0<(B+E)/(A+B+C+D+E)≦0.5 and0<(C+D+E)/(A+B+C+D+E)≦0.8, wherein the polymer contains on the averagefrom more than 0 mol % to 50 mol % of those units derived from indeneand/or substituted indene, and also contains on the average from morethan 0 mol % to 80 mol % of acid labile group-bearing units, based onthe entire polymer, and the polymer has a weight average molecularweight of 3,000 to 100,000.

[0037] In these preferred embodiments, the acid labile group is selectedfrom the class consisting of groups of the following general formulae(4) to (7), tertiary alkyl groups of 4 to 20 carbon atoms, trialkylsilylgroups whose alkyl moieties each have 1 to 6 carbon atoms, oxoalkylgroups of 4 to 20 carbon atoms, and aryl-substituted alkyl groups of 7to 20 carbon atoms.

[0038] Herein R¹⁰ and R¹¹ each are hydrogen or a straight, branched orcyclic alkyl having 1 to 18 carbon atoms, and R¹² is a monovalenthydrocarbon group of 1 to 18 carbon atoms which may contain aheteroatom, a pair of R¹⁰ and R¹¹, R¹⁰ and R¹², or R¹¹ and R¹² maytogether form a ring, with the proviso that R¹⁰, R¹¹, and R¹² each are astraight or branched alkylene of 1 to 18 carbon atoms when they form aring,

[0039] R¹³ is a tertiary alkyl group of 4 to 20 carbon atoms, atrialkysilyl group in which each of the alkyls has 1 to 6 carbon atoms,an oxoalkyl group of 4 to 20 carbon atoms, or a group of the formula(4), z is an integer of 0 to 6,

[0040] R¹⁴ is a straight, branched or cyclic alkyl group of 1 to 8carbon atoms or an aryl group of 6 to 20 carbon atoms which may besubstituted, h is 0 or 1, i is 0, 1, 2 or 3, satisfying 2h+i=2 or 3,

[0041] R¹⁵ is a straight, branched or cyclic alkyl group of 1 to 8carbon atoms or an aryl group of 6 to 20 carbon atoms which may besubstituted, R¹⁶ to R²⁵ are each independently hydrogen or a monovalenthydrocarbon group of 1 to 15 carbon atoms which may contain aheteroatom, any two of R¹⁶ to R²⁵, taken together, may form a ring, eachof the ring-forming two of R¹⁶ to R²⁵ is a divalent hydrocarbon group of1 to 15 carbon atoms which may contain a heteroatom, or two of R¹⁶ toR²⁵ which are attached to adjoining carbon atoms may bond togetherdirectly to form a double bond.

[0042] Preferably, the resist composition contains a propylene glycolalkyl ether acetate, an alkyl lactate or a mixture thereof as theorganic solvent.

[0043] Also contemplated herein is a process for forming a pattern,comprising the steps of applying the resist composition onto a substrateto form a coating; heat treating the coating and exposing the coating tohigh energy radiation with a wavelength of up to 300 nm or electron beamthrough a photomask; optionally heat treating the exposed coating, anddeveloping the coating with a developer.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0044] Sulfonyldiazomethane

[0045] In the first aspect of the invention, novel sulfonyldiazomethanecompounds having a long-chain alkoxyl group are provided. They arerepresented by the general formula (1).

[0046] Herein R is each independently a substituted or unsubstitutedstraight, branched or cyclic alkyl group of 1 to 4 carbon atoms. G isSO₂ or CO. R³ is a substituted or unsubstituted straight, branched orcyclic alkyl group of 1 to 10 carbon atoms or a substituted orunsubstituted aryl group of 6 to 14 carbon atoms. The subscript p is 1or 2, q is 0 or 1, satisfying p+q=2, m is an integer of 3 to 11, and kis an integer of 0 to 4. In the event k is at least 1, at least one of Rassociated with k may bond with the R at the 4-position to form a cyclicstructure with the carbon atoms on the benzene ring to which these R'sare attached, and then, these two R's bond together to form an alkylenegroup of 3 or 4 carbon atoms.

[0047] Preferred among the sulfonyldiazomethane compounds of formula (1)are sulfonyldiazomethane compounds having long-chain alkoxyl groups ofthe following general formula (1a).

[0048] Herein R is each independently a substituted or unsubstitutedstraight, branched or cyclic alkyl group of 1 to 4 carbon atoms, and mis an integer of 3 to 11.

[0049] In formulae (1) and (1a), R may be the same or different andstands for substituted or unsubstituted, straight, branched or cyclicalkyl groups of 1 to 4 carbon atoms, for example, methyl, ethyl,n-propyl, sec-propyl, cyclopropyl, n-butyl, sec-butyl, iso-butyl,tert-butyl, 2-methoxyethyl and trifluoromethyl. A plurality of R groupsmay bond together to form a cyclic structure. In one example, atetramethylene or trimethylene group is attached at the 4,5-positionsrelative to the sulfonyl to form a cyclic structure. Of these, methyl,ethyl, n-propyl, isopropyl and tert-butyl are preferred, with tert-butylbeing most preferred.

[0050] The subscript k is an integer of 0 to 3, and preferably 0, 1 or2. The substitution position of R associated with k is arbitrary.

[0051] R³ stands for substituted or unsubstituted, straight, branched orcyclic alkyl groups of 1 to 10 carbon atoms or substituted orunsubstituted aryl groups of 6 to 14 carbon atoms. Illustrative,non-limiting, examples of the straight, branched or cyclic alkyl groupsinclude methyl, ethyl, n-propyl, sec-propyl, n-butyl, sec-butyl,iso-butyl, tert-butyl, n-pentyl, sec-pentyl, cyclopentyl, n-hexyl, andcyclohexyl. Illustrative, non-limiting, examples of the substituted orunsubstituted aryl groups include phenyl, 4-methylphenyl, 4-ethylphenyl,4-methoxyphenyl, 4-tert-butylphenyl, 4-tert-butoxyphenyl,4-cyclohexylphenyl, 4-cyclohexyloxyphenyl, 2,4-dimethylphenyl,2,4,6-trimethylphenyl, 2,4,6-triisopropylphenyl, 1-naphthyl and2-naphthyl. Of these, tert-butyl, cyclohexyl, 4-methylphenyl,2,4-dimethylphenyl and 4-tert-butylphenyl are preferred. G stands forSO₂ or CO. SO₂ is preferred.

[0052] It is noted that the substituted alkyl groups include halogenatedalkyl groups (e.g., chloro or fluoro-substituted ones),carbonyl-containing alkyl groups, and alkyl groups having a carbonylgroup protected with an acetal (ketal). The substituted aryl groupsinclude halogenated aryl groups (e.g., chloro or fluoro-substitutedones) and straight, branched or cyclic alkoxy group-substituted arylgroups. Specific examples include 2,4-difluorophenyl,4-trifluoromethylphenyl, and groups of the following formulae.

[0053] The subscript p is equal to 1 or 2, q is equal to 0 or 1,satisfying p+q=2. The subscript m is an integer of 3 to 11, preferablyan integer of 3 to 6 as long as the boiling point of intermediatereactants is concerned.

[0054] The sulfonyldiazomethane compounds can be synthesized by thefollowing method although the synthesis method is not limited thereto.

[0055] Reference is first made to a sulfonyldiazomethane compound offormula (1) wherein p=2, that is, a symmetric bissulfonyldiazomethanecompound. It is desirably synthesized by condensing a substitutedthiophenol with dichloromethane under basic conditions as disclosed inJP-A 3-103854. More specifically, a long chain alkoxyl-containingthiophenol such as 2-(n-hexyloxy)-5-tert-butylthiophenol is condensedwith dichloromethane in an alcohol solvent such as methanol or ethanolin the presence of a base such as sodium hydroxide or potassiumhydroxide, obtaining a formaldehyde bis(alkoxyphenylthio)acetal.

[0056] Herein, R, m and k are as defined above.

[0057] Alternatively, a substituted thiophenol is condensed with aformaldehyde (typically paraformaldehyde) under acidic conditions suchas sulfuric acid or trifluoromethanesulfonic acid.

[0058] In the case of p=1, that is, an asymmetric sulfonyldiazomethanecompound, reaction is effected between a halomethyl thioether and analkoxy-substituted thiophenol. In the case ofsulfonylcarbonyldiazomethane, reaction is conducted between anα-halomethylketone and an alkoxy-substituted thiophenol. The halomethylthioether can be prepared from a corresponding thiol, formaldehyde andhydrogen chloride (see J. Am. Chem. Soc., 86, 4383 (1964), J. Am. Chem.Soc., 67, 655 (1945), and U.S. Pat. No. 2,354,229).

[0059] Herein, R, R³, m and k are as defined above, and X is a halogenatom.

[0060] Further, the product is oxidized with an oxidant such as aqueoushydrogen peroxide in the presence of sodium tungstate etc. as describedin JP-A 4-211258, yielding a corresponding sulfonylmethane.

[0061] Herein, R, R³, m and k are as defined above.

[0062] This product is reacted with p-toluenesulfonylazide,p-dodecylbenzenesulfonylazide or p-acetamidobenzenesulfonylazide underbasic conditions into a diazo form, yielding the endsulfonyldiazomethane.

[0063] Herein, R, R³, m and k are as defined above.

[0064] It is noted that the synthesis of alkoxy-substituted thiophenolsis not critical. They can be synthesized by converting an alkoxybenzenewith chlorosulfuric acid, sulfuric acid/acetic anhydride or the like toa substituted benzene sulfonic acid, then converting it withchlorosulfuric acid, thionyl chloride or the like to a substitutedbenzene sulfonyl chloride, and reducing it with aluminum lithiumhydride, hydrochloric acid/zinc or the like as shown below.

[0065] Herein R, m and k are as defined above.

[0066] Alternatively, a halogenated alkoxybenzene is treated withmetallic magnesium to form a Grignard reagent, which is reacted withsulfur and acidified. See Romeo B. Wagner and Harry D. Zook, SyntheticOrganic Chemistry, John Wiley & Sons, Inc., 1965, 778-781.

[0067] Herein R, m and k are as defined above, and X is a halogen atom.

[0068] The halogenated alkoxybenzene can be synthesized by reacting aphenol derivative with CH₃(CH₂)_(m)X under basic conditions, followed byreaction with halogen such as bromine. Exemplary of suitable phenolderivatives are p-cresol, 4-ethylphenol, 4-isopropylphenol,4-tert-butylphenol, 4-(2-methoxyethyl)phenol,5,6,7,8-tetrahydro-2-naphthol, and 5-indanol, with 4-tert-butylphenolbeing preferred.

[0069] Herein R, m and k are as defined above, and X is a halogen atom.

[0070] Examples of the sulfonyldiazomethanes of formulae (1) and (1a)include those of the following structures, but are not limited thereto.

[0071] It is noted that m is an integer of 3 to 11.

[0072] The sulfonyldiazomethane compounds of formula (1) or (1a) areuseful as the photoacid generator in resist materials, especiallychemical amplification type resist materials, which are sensitive toradiation such as ultraviolet, deep ultraviolet, electron beams, x-rays,excimer laser light, γ-rays, and synchrotron radiation, for use in themicrofabrication of integrated circuits.

[0073] Resist Composition

[0074] The resist compositions of the invention contain one or more ofthe sulfonyldiazomethane compounds of formula (1) or (1a). The resistcompositions may be either positive or negative working although theyare preferably of the chemical amplification type. The resistcompositions of the invention include a variety of embodiments,

[0075] 1) a chemically amplified positive working resist compositioncomprising (A) a resin which changes its solubility in an alkalinedeveloper under the action of an acid, (B) a sulfonyldiazomethanecompound capable of generating an acid upon exposure to radiationrepresented by the general formula (1) or (1a), and (F) an organicsolvent;

[0076] 2) a chemically amplified positive working resist compositionof 1) further comprising (C) a photoacid generator capable of generatingan acid upon exposure to radiation other than component (B);

[0077] 3) a chemically amplified positive working resist compositionof 1) or 2) further comprising (D) a basic compound;

[0078] 4) a chemically amplified positive working resist compositionof 1) to 3) further comprising (E) an organic acid derivative;

[0079] 5) a chemically amplified positive working resist compositionof 1) to 4) further comprising (G) a compound with a molecular weight ofup to 3,000 which changes its solubility in an alkaline developer underthe action of an acid;

[0080] 6) a chemically amplified negative working resist compositioncomprising (B) a sulfonyldiazomethane compound capable of generating anacid upon exposure to radiation represented by the general formula (1)or (1a), (F) an organic solvent, (H) an alkali-soluble resin, and (I) anacid crosslinking agent capable of forming a crosslinked structure underthe action of an acid;

[0081] 7) a chemically amplified negative working resist composition of6) further comprising (C) another photoacid generator;

[0082] 8) a chemically amplified negative working resist composition of6) or 7) further comprising (D) a basic compound; and

[0083] 9) a chemically amplified negative working resist composition of6) to 8) further comprising (J) an alkali soluble compound having amolecular weight of up to 2,500; but not limited thereto.

[0084] Now the respective components are described in detail.

[0085] Component (A)

[0086] Component (A) is a resin which changes its solubility in analkaline developer solution under the action of an acid. It ispreferably, though not limited to, an alkali-soluble resin havingphenolic hydroxyl and/or carboxyl groups in which some or all of thephenolic hydroxyl and/or carboxyl groups are protected with acid-labileprotective groups having a C—O—C linkage.

[0087] The alkali-soluble resins having phenolic hydroxyl and/orcarboxyl groups include homopolymers and copolymers of p-hydroxystyrene,m-hydroxystyrene, α-methyl-p-hydroxystyrene, 4-hydroxy-2-methylstyrene,4-hydroxy-3-methylstyrene, hydroxyindene, methacrylic acid and acrylicacid, and copolymers having a carboxylic derivative or diphenyl ethyleneintroduced at the terminus of the foregoing polymers.

[0088] Also included are copolymers in which units free ofalkali-soluble sites such as styrene, α-methylstyrene, acrylate,methacrylate, hydrogenated hydroxystyrene, maleic anhydride, maleimide,substituted or unsubstituted indene are introduced in addition to theabove-described units in such a proportion that the solubility in analkaline developer may not be extremely reduced. Substituents on theacrylates and methacrylates may be any of the substituents which do notundergo acidolysis. Exemplary substituents are straight, branched orcyclic C₁₋₈ alkyl groups and aromatic groups such as aryl groups, butnot limited thereto.

[0089] Examples of the alkali-soluble resins or polymers are givenbelow. These polymers may also be used as the material from which theresin (A) which changes its solubility in an alkaline developer underthe action of an acid is prepared and as the alkali-soluble resin whichserves as component (H) to be described later. Examples includepoly(p-hydroxystyrene), poly(m-hydroxystyrene),poly(4-hydroxy-2-methylstyrene), poly(4-hydroxy-3-methylstyrene),poly(α-methyl-p-hydroxystyrene), partially hydrogenated p-hydroxystyrenecopolymers, p-hydroxystyrene-α-methyl-p-hydroxystyrene copolymers,p-hydroxystyrene-α-methylstyrene copolymers, p-hydroxystyrene-styrenecopolymers, p-hydroxystyrene-m-hydroxystyrene copolymers,p-hydroxystyrene-styrene copolymers, p-hydroxystyrene-indene copolymers,p-hydroxystyrene-acrylic acid copolymers, p-hydroxystyrene-methacrylicacid copolymers, p-hydroxystyrene-methyl acrylate copolymers,p-hydroxystyrene-acrylic acid-methyl methacrylate copolymers,p-hydroxystyrene-methyl methacrylate copolymers,p-hydroxystyrene-methacrylic acid-methyl methacrylate copolymers,poly(methacrylic acid), poly(acrylic acid), acrylic acid-methyl acrylatecopolymers, methacrylic acid-methyl methacrylate copolymers, acrylicacid-maleimide copolymers, methacrylic acid-maleimide copolymers,p-hydroxystyrene-acrylic acid-maleimide copolymers, andp-hydroxystyrene-methacrylic acid-maleimide copolymers, but are notlimited to these combinations.

[0090] Preferred are poly(p-hydroxystyrene), partially hydrogenatedp-hydroxystyrene copolymers, p-hydroxystyrene-styrene copolymers,p-hydroxystyrene-indene copolymers, p-hydroxystyrene-acrylic acidcopolymers, and p-hydroxystyrene-methacrylic acid copolymers.

[0091] Alkali-soluble resins comprising units of the following formula(2), (2′) or (2″) are especially preferred.

[0092] Herein R⁴ is hydrogen or methyl, R⁵ is a straight, branched orcyclic alkyl group of 1 to 8 carbon atoms, x is 0 or a positive integer,y is a positive integer, satisfying x+y≦5, M and N are positiveintegers, satisfying 0<N/(M+N)≦0.5, and A and B are positive integers,and C is 0 or a positive integer, satisfying 0<B/(A+B+C)≦0.5.

[0093] The polymer of formula (2″) can be synthesized, for example, byeffecting thermal polymerization of an acetoxystyrene monomer, atertiary alkyl(meth)acrylate monomer and an indene monomer in an organicsolvent in the presence of a radical initiator, and subjecting theresulting polymer to alkaline hydrolysis in an organic solvent fordeblocking the acetoxy group, for thereby forming a ternary copolymer ofhydroxystyrene, tertiary alkyl(meth)acrylate and indene. The organicsolvent used during polymerization is exemplified by toluene, benzene,tetrahydrofuran, diethyl ether and dioxane. Exemplary polymerizationinitiators include 2,2′-azobisisobutyronitrile,2,2′-azobis(2,4-dimethylvaleronitrile),dimethyl-2,2-azobis(2-methylpropionate), benzoyl peroxide, and lauroylperoxide. Polymerization is preferably effected while heating at 50 to80° C. The reaction time is usually about 2 to 100 hours, preferablyabout 5 to 20 hours. Aqueous ammonia, triethylamine or the like may beused as the base for the alkaline hydrolysis. For the alkalinehydrolysis, the temperature is usually −20° C. to 100° C., preferably 0°C. to 60° C., and the time is about 0.2 to 100 hours, preferably about0.5 to 20 hours.

[0094] Also included are polymers having the dendritic or hyperbranchedpolymer structure of formula (2″′) below.

[0095] Herein ZZ is a divalent organic group selected from among CH₂,CH(OH), CR⁵(OH), C═O and C(OR⁵)(OH) or a trivalent organic grouprepresented by —C(OH)═. Subscript F, which may be identical ordifferent, is a positive integer, and H is a positive integer,satisfying 0.001≦H/(H+F)≦0.1, and XX is 1 or 2. R⁴, R⁵, x and y are asdefined above.

[0096] The dendritic or hyperbranched polymer of phenol derivative canbe synthesized by effecting living anion polymerization of apolymerizable monomer such as 4-tert-butoxystyrene and reacting abranching monomer such as chloromethylstyrene as appropriate during theliving anion polymerization. For the detail of synthesis, reference ismade to JP-A 2000-344836.

[0097] The alkali-soluble resins or polymers should preferably have aweight average molecular weight (Mw) of 3,000 to 100,000. Many polymerswith Mw of less than 3,000 do not perform well and are poor in heatresistance and film formation. Many polymers with Mw of more than100,000 give rise to a problem with respect to dissolution in the resistsolvent and developer. The polymer should also preferably have adispersity (Mw/Mn) of up to 3.5, and more preferably up to 1.5. With adispersity of more than 3.5, resolution is low in many cases. Althoughthe preparation method is not critical, a poly(p-hydroxystyrene) orsimilar polymer with a low dispersity or narrow dispersion can besynthesized by living anion polymerization.

[0098] In the resist composition using the sulfonyldiazomethane offormula (1), a resin having such substituent groups with C—O—C linkages(acid labile groups) that the solubility in an alkaline developerchanges as a result of severing of the C—O—C linkages under the actionof an acid, especially an alkali-soluble resin as mentioned above ispreferably used as component (A). Especially preferred is a polymercomprising recurring units of the above formula (2) and containingphenolic hydroxyl groups in which hydrogen atoms of the phenolichydroxyl groups are substituted with acid labile groups of one or moretypes in a proportion of more than 0 molt to 80 molt on the average ofthe entire hydrogen atoms of the phenolic hydroxyl group, the polymerhaving a weight average molecular weight of 3,000 to 100,000.

[0099] Also preferred is a polymer comprising recurring units of theabove formula (2′), that is, a copolymer comprising p-hydroxystyreneand/or α-methyl-p-hydroxystyrene and acrylic acid and/or methacrylicacid, wherein some of the hydrogen atoms of the carboxyl groups ofacrylic acid and/or methacrylic acid are substituted with acid labilegroups of one or more types, and the units derived from acrylate and/ormethacrylate are contained in a proportion of more than 0 molt to 50molt, on the average, of the copolymer, and wherein some of the hydrogenatoms of the phenolic hydroxyl groups of p-hydroxystyrene and/orα-methyl-p-hydroxystyrene may be substituted with acid labile groups ofone or more types. In the preferred copolymer, the units derived fromacrylate and/or methacrylate and the units derived from p-hydroxystyreneand/or α-methyl-p-hydroxystyrene optionally having acid labile groupssubstituted thereon are contained in a proportion of more than 0 molt to80 molt, on the average, of the copolymer.

[0100] Alternatively, a polymer comprising recurring units of the aboveformula (2″), that is, a copolymer comprising p-hydroxystyrene and/orα-methyl-p-hydroxystyrene and substituted and/or unsubstituted indene,is preferred wherein some of the hydrogen atoms of the phenolic hydroxylgroups of p-hydroxystyrene and/or α-methyl-p-hydroxystyrene aresubstituted with acid labile groups of one or more types, and some ofthe hydrogen atoms of the carboxyl groups of acrylic acid and/ormethacrylic acid are substituted with acid labile groups of one or moretypes. Where the substituted indene has hydroxyl groups, some of thehydrogen atoms of these hydroxyl groups may be substituted with acidlabile groups of one or more types. In the preferred copolymer, theunits derived from p-hydroxystyrene and/or α-methyl-p-hydroxystyrenehaving acid labile groups substituted thereon, the units derived fromacrylic acid and/or methacrylic acid having acid labile groupssubstituted thereon, and the units derived from indene having acidlabile groups substituted thereon are contained in a proportion of morethan 0 molt to 80 molt, on the average, of the copolymer.

[0101] Exemplary and preferred such polymers are polymers or highmolecular weight compounds comprising recurring units represented by thefollowing general formula (2a), (2a′) or (2a″) and having a weightaverage molecular weight of 3,000 to 100,000.

[0102] Herein, R⁴ is hydrogen or methyl. R⁵ is a straight, branched orcyclic alkyl group of 1 to 8 carbon atoms. Letter x is 0 or a positiveinteger, and y is a positive integer, satisfying x+y≦5. R⁶ is an acidlabile group. S and T are positive integers, satisfying 0<T/(S+T)≦0.8.R^(6a) is hydrogen or an acid labile group, at least some of the R^(6a)groups are acid labile groups. M and N are positive integers, L is 0 ora positive integer, satisfying 0<N/(M+N+L)≦0.5 and 0<(N+L)/(M+N+L)≦0.5.The letter yy is 0 or a positive integer, satisfying x+yy≦5. A and B arepositive integers, C, D and E each are 0 or a positive integer,satisfying 0<(B+E)/(A+B+C+D+E)≦0.5 and 0<(C+D+E)/(A+B+C+D+E)≦0.8.

[0103] R⁵ stands for straight, branched or cyclic C₁₋₈ alkyl groups, forexample, methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl,tert-butyl, cyclohexyl and cyclopentyl.

[0104] With respect to the acid labile groups, where some of thephenolic hydroxyl groups and some or all of the carboxyl groups in thealkali-soluble resin are protected with acid labile groups having C—O—Clinkages, the acid labile groups are selected from a variety of suchgroups. The preferred acid labile groups are groups of the followinggeneral formulae (4) to (7), tertiary alkyl groups of 4 to 20 carbonatoms, preferably 4 to 15 carbon atoms, trialkylsilyl groups whose alkylgroups each have 1 to 6 carbon atoms, oxoalkyl groups of 4 to 20 carbonatoms, or aryl-substituted alkyl groups of 7 to 20 carbon atoms.

[0105] Herein R¹⁰ and R¹¹ are independently hydrogen or straight,branched or cyclic alkyl groups of 1 to 18 carbon atoms, preferably 1 to10 carbon atoms, for example, methyl, ethyl, propyl, isopropyl, n-butyl,sec-butyl, tert-butyl, cyclopentyl, cyclohexyl, 2-ethylhexyl andn-octyl. R¹² is a monovalent hydrocarbon group of 1 to 18 carbon atoms,preferably 1 to 10 carbon atoms, which may have a hetero atom (e.g.,oxygen atom), for example, straight, branched or cyclic alkyl groups,and such groups in which some hydrogen atoms are substituted withhydroxyl, alkoxy, oxo, amino or alkylamino groups. Illustrative examplesof the substituted alkyl groups are given below.

[0106] A pair of R¹⁰ and R¹¹, a pair of R¹⁰ and R¹², or a pair of R¹¹and R¹², taken together, may form a ring. Each of R¹⁰, R¹¹ and R¹² is astraight or branched alkylene group of 1 to 18 carbon atoms, preferably1 to 10 carbon atoms, when they form a ring.

[0107] R¹³ is a tertiary alkyl group of 4 to 20 carbon atoms, preferably4 to 15 carbon atoms, a trialkylsilyl group whose alkyl groups each have1 to 6 carbon atoms, an oxoalkyl group of 4 to 20 carbon atoms or agroup of formula (4). Exemplary tertiary alkyl groups are tert-butyl,tert-amyl, 1,1-diethylpropyl, 1-ethylcyclopentyl, 1-butylcyclopentyl,1-ethylcyclohexyl, 1-butylcyclohexyl, 1-ethyl-2-cyclopentenyl,1-ethyl-2-cyclohexenyl, 2-methyl-2-adamantyl, 2-ethyl-2-adamantyl and1-adamantyl-1-methylethyl. Exemplary trialkylsilyl groups aretrimethylsilyl, triethylsilyl, and dimethyl-tert-butylsilyl. Exemplaryoxoalkyl groups are 3-oxocyclohexyl, 4-methyl-2-oxooxan-4-yl, and5-methyl-5-oxooxolan-4-yl. Letter z is an integer of 0 to 6.

[0108] R¹⁴ is a straight, branched or cyclic alkyl group of 1 to 8carbon atoms or substituted or unsubstituted aryl group of 6 to 20carbon atoms. Exemplary straight, branched or cyclic alkyl groupsinclude methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl,tert-butyl, tert-amyl, n-pentyl, n-hexyl, cyclopentyl, cyclohexyl,cyclopentylmethyl, cyclopentylethyl, cyclohexylmethyl andcyclohexylethyl. Exemplary substituted or unsubstituted aryl groupsinclude phenyl, methylphenyl, naphthyl, anthryl, phenanthryl, andpyrenyl. Letter h is equal to 0 or 1, i is equal to 0, 1, 2 or 3,satisfying 2h+i=2 or 3.

[0109] R¹⁵ is a straight, branched or cyclic alkyl group of 1 to 8carbon atoms or substituted or unsubstituted aryl group of 6 to 20carbon atoms, examples of which are as exemplified for R¹⁴. R¹⁶ to R²⁵are independently hydrogen or monovalent hydrocarbon groups of 1 to 15carbon atoms which may contain a hetero atom, for example, straight,branched or cyclic alkyl groups such as methyl, ethyl, propyl,isopropyl, n-butyl, sec-butyl, tert-butyl, tert-amyl, n-pentyl, n-hexyl,n-octyl, n-nonyl, n-decyl, cyclopentyl, cyclohexyl, cyclopentylmethyl,cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl,and cyclohexylbutyl, and substituted ones of these groups in which somehydrogen atoms are substituted with hydroxyl, alkoxy, carboxy,alkoxycarbonyl, oxo, amino, alkylamino, cyano, mercapto, alkylthio, andsulfo groups. R¹⁶ to R²⁵, for example, a pair of R¹⁶ and R¹⁷, a pair ofR¹⁶ and R¹⁸, a pair of R¹⁷ and R¹⁹, a pair of R¹⁸ and R¹⁹, a pair of R²⁰and R²¹, or a pair of R²² and R²³, taken together, may form a ring. WhenR¹⁶ to R²⁶ form a ring, they are divalent hydrocarbon groups of 1 to 15carbon atoms which may contain a hetero atom, examples of which are theabove-exemplified monovalent hydrocarbon groups with one hydrogen atomeliminated. Also, two of R¹⁶ to R²⁵ which are attached to adjacentcarbon atoms (for example, a pair of R¹⁶ and R¹⁸, a pair of R¹⁸ and R²⁴or a pair of R²² and R²⁴) may directly bond together to form a doublebond.

[0110] Of the acid labile groups of formula (4), illustrative examplesof the straight or branched groups are given below.

[0111] Of the acid labile groups of formula (4), illustrative examplesof the cyclic groups include tetrahydrofuran-2-yl,2-methyltetrahydrofuran-2-yl, tetrahydropyran-2-yl and2-methyltetrahydropyran-2-yl.

[0112] Illustrative examples of the acid labile groups of formula (5)include tert-butoxycarbonyl, tert-butoxycarbonylmethyl,tert-amyloxycarbonyl, tert-amyloxycarbonylmethyl,1,1-diethylpropyloxycarbonyl, 1,1-diethylpropyloxycarbonylmethyl,1-ethylcyclopentyloxycarbonyl, 1-ethylcyclopentyloxycarbonylmethyl,1-ethyl-2-cyclopentenyloxycarbonyl,1-ethyl-2-cyclopentenyloxycarbonylmethyl, 1-ethoxyethoxycarbonylmethyl,2-tetrahydropyranyloxycarbonylmethyl, and2-tetrahydrofuranyloxycarbonylmethyl.

[0113] Illustrative examples of the acid labile groups of formula (6)include 1-methylcyclopentyl, 1-ethylcyclopentyl, 1-n-propylcyclopentyl,1-isopropylcyclopentyl, 1-n-butylcyclopentyl, 1-sec-butylcyclopentyl,1-methylcyclohexyl, 1-ethylcyclohexyl, 3-methyl-1-cyclopenten-3-yl,3-ethyl-1-cyclopenten-3-yl, 3-methyl-1-cyclohexen-3-yl,3-ethyl-1-cyclohexen-3-yl, and 1-cyclohexyl-cyclopentyl.

[0114] Illustrative examples of the acid labile groups of formula (7)are given below.

[0115] Exemplary of the tertiary alkyl group of 4 to 20 carbon atoms,preferably 4 to 15 carbon atoms, are tert-butyl, tert-amyl,1,1-diethylpropyl, 1-ethylcyclopentyl, 1-butylcyclopentyl,1-ethylcyclohexyl, 1-butylcyclohexyl, 1-ethyl-2-cyclopentenyl,1-ethyl-2-cyclohexenyl, 2-methyl-2-adamantyl, 2-ethyl-2-adamantyl,1-adamantyl-1-methylethyl, 3-ethyl-3-pentyl and dimethylbenzyl.

[0116] Exemplary of the trialkylsilyl groups whose alkyl groups eachhave 1 to 6 carbon atoms are trimethylsilyl, triethylsilyl, andtert-butyldimethylsilyl.

[0117] Exemplary of the oxoalkyl groups of 4 to 20 carbon atoms are3-oxocyclohexyl and groups represented by the following formulae.

[0118] Exemplary of the aryl-substituted alkyl groups of 7 to 20 carbonatoms are benzyl, methylbenzyl, dimethylbenzyl, diphenylmethyl, and1,1-diphenylethyl.

[0119] In the resist composition comprising the sulfonyldiazomethane asa photoacid generator, the resin (A) which changes its solubility in analkaline developer under the action of an acid may be the polymer offormula (2) or (2′), (2″) or (2″′) in which some of the hydrogen atomsof the phenolic hydroxyl groups are crosslinked within a molecule and/orbetween molecules, in a proportion of more than 0 mol % to 50 mol %, onthe average, of the entire phenolic hydroxyl groups on the polymer, withcrosslinking groups having C—O—C linkages represented by the followinggeneral formula (3). With respect to illustrative examples and synthesisof polymers crosslinked with acid labile groups, reference should bemade to JP-A 11-190904.

[0120] Herein, each of R⁷ and R⁸ is hydrogen or a straight, branched orcyclic alkyl group of 1 to 8 carbon atoms, or R⁷ and R⁸, taken together,may form a ring, and each of R⁷ and R⁸ is a straight or branchedalkylene group of 1 to 8 carbon atoms when they form a ring. R⁹ is astraight, branched or cyclic alkylene group of 1 to 10 carbon atoms.Letter “b” is 0 or an integer of 1 to 10. AA is an a-valent aliphatic oralicyclic saturated hydrocarbon group, aromatic hydrocarbon group orheterocyclic group of 1 to 50 carbon atoms, which may be separated by ahetero atom and in which some of the hydrogen atom attached to carbonatoms may be substituted with hydroxyl, carboxyl, carbonyl or halogen.Letter “a” is an integer of 1 to 7.

[0121] Preferably in formula (3), R⁷ is methyl, R⁸ is hydrogen, “a” is1, “b” is 0, and AA is ethylene, 1,4-butylene or 1,4-cyclohexylene.

[0122] It is noted that these polymers which are crosslinked within themolecule or between molecules with crosslinking groups having C—O—Clinkages can be synthesized by reacting a corresponding non-crosslinkedpolymer with an alkenyl ether in the presence of an acid catalyst in aconventional manner.

[0123] If decomposition of other acid labile groups proceeds under acidcatalyst conditions, the end product can be obtained by once reactingthe alkenyl ether with hydrochloric acid or the like for conversion to ahalogenated alkyl ether and reacting it with the polymer under basicconditions in a conventional manner.

[0124] Illustrative, non-limiting, examples of the alkenyl ether includeethylene glycol divinyl ether, triethylene glycol divinyl ether,1,2-propanediol divinyl ether, 1,3-propanediol divinyl ether,1,3-butanediol divinyl ether, 1,4-butanediol divinyl ether, neopentylglycol divinyl ether, trimethylolpropane trivinyl ether,trimethylolethane trivinyl ether, hexanediol divinyl ether, and1,4-cyclohexanediol divinyl ether.

[0125] In the chemical amplification type positive resist composition,the resin used as component (A) is as described above while thepreferred acid labile groups to be substituted for phenolic hydroxylgroups are 1-ethoxyethyl, 1-ethoxypropyl, tetrahydrofuranyl,tetrahydropyranyl, tert-butyl, tert-amyl,1-ethylcyclohexyloxycarbonylmethyl, tert-butoxycarbonyl,tert-butoxycarbonylmethyl, and substituents of formula (3) wherein R⁷ ismethyl, R⁸ is hydrogen, “a” is 1, “b” is 0, and AA is ethylene,1,4-butylene or 1,4-cyclohexylene. Also preferably, the hydrogen atomsof carboxyl groups of methacrylic acid or acrylic acid are protectedwith substituent groups as typified by tert-butyl, tert-amyl,2-methyl-2-adamantyl, 2-ethyl-2-adamantyl, 1-ethylcyclopentyl,1-ethylcyclohexyl, 1-cyclohexylcyclopentyl, 1-ethylnorbornyl,tetrahydrofuranyl and tetrahydropyranyl.

[0126] In a single polymer, these substituents may be incorporated aloneor in admixture of two or more types. A blend of two or more polymershaving substituents of different types is also acceptable.

[0127] The percent proportion of these substituents substituting forphenol and carboxyl groups in the polymer is not critical. Preferablythe percent substitution is selected such that when a resist compositioncomprising the polymer is applied onto a substrate to form a coating,the unexposed area of the coating may have a dissolution rate of 0.01 to10 Å/sec in a 2.38% tetramethylammonium hydroxide (TMAH) developer.

[0128] On use of a polymer containing a greater proportion of carboxylgroups which can reduce the alkali dissolution rate, the percentsubstitution must be increased or non-acid-decomposable substituents tobe described later must be introduced.

[0129] When acid labile groups for intramolecular and/or intermolecularcrosslinking are to be introduced, the percent proportion ofcrosslinking substituents is preferably up to 20 mol %, more preferablyup to 10 mol %, based on the entire hydrogen atoms of phenolic hydroxylgroups. If the percent substitution of crosslinking substituents is toohigh, crosslinking results in a higher molecular weight which canadversely affect dissolution, stability and resolution. It is alsopreferred to further introduce another non-crosslinking acid labilegroup into the crosslinked polymer at a percent substitution of up to 10mol % for adjusting the dissolution rate to fall within the above range.

[0130] In the case of poly(p-hydroxystyrene), the optimum percentsubstitution differs between a substituent having a strong dissolutioninhibitory action such as a tert-butoxycarbonyl group and a substituenthaving a weak dissolution inhibitory action such as an acetal groupalthough the overall percent substitution is preferably 10 to 40 mol %,more preferably 20 to 30 mol %, based on the entire hydrogen atoms ofphenolic hydroxyl groups in the polymer.

[0131] Polymers having such acid labile groups introduced therein shouldpreferably have a weight average molecular weight (Mw) of 3,000 to100,000. With a Mw of less than 3,000, polymers would perform poorly andoften lack heat resistance and film formability. Polymers with a Mw ofmore than 100,000 would be less soluble in a developer and a resistsolvent.

[0132] Where non-crosslinking acid labile groups are introduced, thepolymer should preferably have a dispersity (Mw/Mn) of up to 3.5,preferably up to 1.5. A polymer with a dispersity of more than 3.5 oftenresults in a low resolution. Where crosslinking acid labile groups areintroduced, the starting alkali-soluble resin should preferably have adispersity (Mw/Mn) of up to 1.5, and the dispersity is kept at 3 orlower even after protection with crosslinking acid labile groups. If thedispersity is higher than 3, dissolution, coating, storage stabilityand/or resolution is often poor.

[0133] To impart a certain function, suitable substituent groups may beintroduced into some of the phenolic hydroxyl and carboxyl groups on theacid labile group-protected polymer. Exemplary are substituent groupsfor improving adhesion to the substrate, non-acid-labile groups foradjusting dissolution in an alkali developer, and substituent groups forimproving etching resistance. Illustrative, non-limiting, substituentgroups include 2-hydroxyethyl, 2-hydroxypropyl, methoxymethyl,methoxycarbonyl, ethoxycarbonyl, methoxycarbonylmethyl,ethoxycarbonylmethyl, 4-methyl-2-oxo-4-oxolanyl,4-methyl-2-oxo-4-oxanyl, methyl, ethyl, propyl, n-butyl, sec-butyl,acetyl, pivaloyl, adamantyl, isobornyl, and cyclohexyl.

[0134] In the resist composition of the invention, the above-describedresin is added in any desired amount, and usually 65 to 99 parts byweight, preferably 70 to 98 parts by weight per 100 parts by weight ofthe solids in the composition. The term “solids” is used to encompassall components in the resist composition excluding the solvent.

[0135] Illustrative examples of the sulfonyldiazomethane compounds offormulae (1) and (1a) as the photoacid generator (B) are as describedabove. Listing again, examples of bilaterally symmetricbissulfonyldiazomethane include, but are not limited to,

[0136] bis(2-(n-butyloxy)-5-methylbenzenesulfonyl)diazomethane,

[0137] bis(2-(n-pentyloxy)-5-methylbenzenesulfonyl)diazomethane,

[0138] bis(2-(n-hexyloxy)-5-methylbenzenesulfonyl)diazomethane,

[0139] bis(2-(n-heptyloxy)-5-methylbenzenesulfonyl)diazomethane,

[0140] bis(2-(n-octyloxy)-5-methylbenzenesulfonyl)diazomethane,

[0141] bis(2-(n-nonyloxy)-5-methylbenzenesulfonyl)diazomethane,

[0142] bis(2-(n-butyloxy)-5-ethylbenzenesulfonyl)diazomethane,

[0143] bis(2-(n-pentyloxy)-5-ethylbenzenesulfonyl)diazomethane,

[0144] bis(2-(n-hexyloxy)-5-ethylbenzenesulfonyl)diazomethane,

[0145] bis(2-(n-heptyloxy)-5-ethylbenzenesulfonyl)diazomethane,

[0146] bis(2-(n-octyloxy)-5-ethylbenzenesulfonyl)diazomethane,

[0147] bis(2-(n-nonyloxy)-5-ethylbenzenesulfonyl)diazomethane,

[0148] bis(2-(n-butyloxy)-5-isopropylbenzenesulfonyl)diazomethane,

[0149] bis(2-(n-pentyloxy)-5-isopropylbenzenesulfonyl)diazomethane,

[0150] bis(2-(n-hexyloxy)-5-isopropylbenzenesulfonyl)diazomethane,

[0151] bis(2-(n-heptyloxy)-5-isopropylbenzenesulfonyl)diazomethane,

[0152] bis(2-(n-octyloxy)-5-isopropylbenzenesulfonyl)diazomethane,

[0153] bis(2-(n-nonyloxy)-5-isopropylbenzenesulfonyl)diazomethane,

[0154] bis(2-(n-butyloxy)-5-tert-butylbenzenesulfonyl)diazomethane,

[0155] bis(2-(n-pentyloxy)-5-tert-butylbenzenesulfonyl)diazomethane,

[0156] bis(2-(n-hexyloxy)-5-tert-butylbenzenesulfonyl)diazomethane,

[0157] bis(2-(n-heptyloxy)-5-tert-butylbenzenesulfonyl)diazomethane,

[0158] bis(2-(n-octyloxy)-5-tert-butylbenzenesulfonyl)diazomethane,

[0159] bis(2-(n-nonyloxy)-5-tert-butylbenzenesulfonyl)diazomethane, etc.Of these, preferred are

[0160] bis(2-(n-butyloxy)-5-tert-butylbenzenesulfonyl)diazomethane,

[0161] bis(2-(n-pentyloxy)-5-tert-butylbenzenesulfonyl)diazomethane,

[0162] and bis(2-(n-hexyloxy)-5-tert-butylbenzenesulfonyl)diazomethane.

[0163] Examples of bilaterally asymmetric sulfonyldiazomethane include,but are not limited to,

[0164](2-(n-butyloxy)-5-methylbenzenesulfonyl)(tert-butylsulfonyl)diazomethane,

[0165](2-(n-pentyloxy)-5-methylbenzenesulfonyl)(tert-butylsulfonyl)diazomethane,

[0166](2-(n-hexyloxy)-5-methylbenzenesulfonyl)(tert-butylsulfonyl)diazomethane,

[0167](2-(n-butyloxy)-5-tert-butylbenzenesulfonyl)(tert-butylsulfonyl)diazomethane,

[0168](2-(n-pentyloxy)-5-tert-butylbenzenesulfonyl)(tert-butylsulfonyl)diazomethane,

[0169](2-(n-hexyloxy)-5-tert-butylbenzenesulfonyl)(tert-butylsulfonyl)diazomethane,

[0170](2-(n-butyloxy)-5-methylbenzenesulfonyl)(cyclohexylsulfonyl)diazomethane,

[0171](2-(n-pentyloxy)-5-methylbenzenesulfonyl)(cyclohexylsulfonyl)diazomethane,

[0172](2-(n-hexyloxy)-5-methylbenzenesulfonyl)(cyclohexylsulfonyl)diazomethane,

[0173](2-(n-butyloxy)-5-tert-butylbenzenesulfonyl)(cyclohexylsulfonyl)diazomethane,

[0174](2-(n-pentyloxy)-5-tert-butylbenzenesulfonyl)(cyclohexylsulfonyl)diazomethane,

[0175](2-(n-hexyloxy)-5-tert-butylbenzenesulfonyl)(cyclohexylsulfonyl)diazomethane,

[0176](2-(n-butyloxy)-5-methylbenzenesulfonyl)(2,4-dimethylbenzenesulfonyl)diazomethane,

[0177](2-(n-pentyloxy)-5-methylbenzenesulfonyl)(2,4-dimethylbenzenesulfonyl)diazomethane,

[0178](2-(n-hexyloxy)-5-methylbenzenesulfonyl)(2,4-dimethylbenzenesulfonyl)diazomethane,

[0179](2-(n-butyloxy)-5-tert-butylbenzenesulfonyl)(2,4-dimethylbenzenesulfonyl)diazomethane,

[0180](2-(n-pentyloxy)-5-tert-butylbenzenesulfonyl)(2,4-dimethylbenzenesulfonyl)diazomethane,

[0181](2-(n-hexyloxy)-5-tert-butylbenzenesulfonyl)(2,4-dimethylbenzenesulfonyl)diazomethane,

[0182](2-(n-butyloxy)-5-methylbenzenesulfonyl)(2-naphthalenesulfonyl)diazomethane,

[0183](2-(n-pentyloxy)-5-methylbenzenesulfonyl)(2-naphthalenesulfonyl)diazomethane,

[0184](2-(n-hexyloxy)-5-methylbenzenesulfonyl)(2-naphthalenesulfonyl)diazomethane,

[0185](2-(n-butyloxy)-5-tert-butylbenzenesulfonyl)(2-naphthalenesulfonyl)diazomethane,

[0186](2-(n-pentyloxy)-5-tert-butylbenzenesulfonyl)(2-naphthalenesulfonyl)diazomethane,

[0187](2-(n-hexyloxy)-5-tert-butylbenzenesulfonyl)(2-naphthalenesulfonyl)diazomethane,etc.

[0188] Examples of the sulfonyl-carbonyldiazomethane include, but arenot limited to,

[0189](2-(n-butyloxy)-5-methylbenzenesulfonyl)(tert-butylcarbonyl)diazomethane,

[0190](2-(n-pentyloxy)-5-methylbenzenesulfonyl)(tert-butylcarbonyl)diazomethane,

[0191](2-(n-hexyloxy)-5-methylbenzenesulfonyl)(tert-butylcarbonyl)diazomethane,

[0192](2-(n-butyloxy)-5-tert-butylbenzenesulfonyl)(tert-butylcarbonyl)diazomethane,

[0193](2-(n-pentyloxy)-5-tert-butylbenzenesulfonyl)(tert-butylcarbonyl)diazomethane,

[0194](2-(n-hexyloxy)-5-tert-butylbenzenesulfonyl)(tert-butylcarbonyl)diazomethane,

[0195](2-(n-butyloxy)-5-methylbenzenesulfonyl)(benzenecarbonyl)diazomethane,

[0196](2-(n-pentyloxy)-5-methylbenzenesulfonyl)(benzenecarbonyl)diazomethane,

[0197](2-(n-hexyloxy)-5-methylbenzenesulfonyl)(benzenecarbonyl)diazomethane,

[0198](2-(n-butyloxy)-5-tert-butylbenzenesulfonyl)(benzenecarbonyl)diazomethane,

[0199](2-(n-pentyloxy)-5-tert-butylbenzenesulfonyl)(benzenecarbonyl)diazomethane,

[0200](2-(n-hexyloxy)-5-tert-butylbenzenesulfonyl)(benzenecarbonyl)diazomethane,

[0201](2-(n-butyloxy)-5-methylbenzenesulfonyl)(2-naphthalenecarbonyl)diazomethane,

[0202](2-(n-pentyloxy)-5-methylbenzenesulfonyl)(2-naphthalenecarbonyl)diazomethane,

[0203](2-(n-hexyloxy)-5-methylbenzenesulfonyl)(2-naphthalenecarbonyl)diazomethane,

[0204](2-(n-butyloxy)-5-tert-butylbenzenesulfonyl)(2-naphthalenecarbonyl)diazomethane,

[0205](2-(n-pentyloxy)-5-tert-butylbenzenesulfonyl)(2-naphthalenecarbonyl)diazomethane,

[0206](2-(n-hexyloxy)-5-tert-butylbenzenesulfonyl)(2-naphthalenecarbonyl)diazomethane,etc.

[0207] In the chemical amplification resist composition, an appropriateamount of the sulfonyldiazomethane compound of formula (1) or (1a) addedis from more than 0 part to 10 parts by weight, and preferably from 1 to5 parts by weight, per 100 parts by weight of the solids in thecomposition. The sulfonyldiazomethane compound is used at least in anamount to generate a sufficient amount of acid to deblock acid labilegroups in the polymer. Too large amounts may excessively reduce thetransmittance of resist film, failing to form a rectangular pattern, andgive rise to problems of abnormal particles and deposits during resiststorage. The photoacid generators may be used alone or in admixture oftwo or more.

[0208] Component (C)

[0209] In one preferred embodiment, the resist composition furthercontains (C) a compound capable of generating an acid upon exposure tohigh energy radiation, that is, a second photoacid generator other thanthe sulfonyldiazomethane (B) having formula (1) or (1a). Suitable secondphotoacid generators include sulfonium salts, iodonium salts,sulfonyldiazomethane and N-sulfonyloxyimide photoacid generators.Exemplary second photoacid generators are given below while they may beused alone or in admixture of two or more.

[0210] Sulfonium salts are salts of sulfonium cations with sulfonates.Exemplary sulfonium cations include triphenylsulfonium,(4-tert-butoxyphenyl)diphenylsulfonium,bis(4-tert-butoxyphenyl)phenylsulfonium,tris(4-tert-butoxyphenyl)sulfonium,(3-tert-butoxyphenyl)diphenylsulfonium,bis(3-tert-butoxyphenyl)phenylsulfonium,tris(3-tert-butoxyphenyl)sulfonium,(3,4-di-tert-butoxyphenyl)diphenylsulfonium,bis(3,4-di-tert-butoxyphenyl)phenylsulfonium,tris(3,4-di-tert-butoxyphenyl)sulfonium,diphenyl(4-thiophenoxyphenyl)sulfonium,(4-tert-butoxycarbonylmethyloxyphenyl)diphenylsulfonium,tris(4-tert-butoxycarbonylmethyloxyphenyl)sulfonium,(4-tert-butoxyphenyl)bis(4-dimethylaminophenyl)sulfonium,tris(4-dimethylaminophenyl)sulfonium, 2-naphthyldiphenylsulfonium,dimethyl-2-naphthylsulfonium, 4-hydroxyphenyldimethylsulfonium,4-methoxyphenyldimethylsulfonium, trimethylsulfonium,2-oxocyclohexylcyclohexylmethylsulfonium, trinaphthylsulfonium,tribenzylsulfonium, diphenylmethylsulfonium, dimethylphenylsulfonium,and 2-oxo-2-phenylethylthiacyclopentanium. Exemplary sulfonates includetrifluoromethanesulfonate, nonafluorobutanesulfonate,heptadecafluorooctanesulfonate, 2,2,2-trifluoroethanesulfonate,pentafluorobenzenesulfonate, 4-trifluoromethylbenzenesulfonate,4-fluorobenzenesulfonate, mesitylenesulfonate,2,4,6-triisopropylbenzenesulfonate, toluenesulfonate, benzenesulfonate,4-(4′-toluenesulfonyloxy)benzenesulfonate, naphthalenesulfonate,camphorsulfonate, octanesulfonate, dodecylbenzenesulfonate,butanesulfonate, and methanesulfonate. Sulfonium salts based oncombination of the foregoing examples are included.

[0211] Iodinium salts are salts of iodonium cations with sulfonates.Exemplary iodinium cations are aryliodonium cations includingdiphenyliodinium, bis(4-tert-butylphenyl)iodonium,4-tert-butoxyphenylphenyliodonium, and 4-methoxyphenylphenyliodonium.Exemplary sulfonates include trifluoromethanesulfonate,nonafluorobutanesulfonate, heptadecafluorooctanesulfonate,2,2,2-trifluoroethanesulfonate, pentafluorobenzenesulfonate,4-trifluoromethylbenzenesulfonate, 4-fluorobenzenesulfonate,mesitylenesulfonate, 2,4,6-triisopropylbenzenesulfonate,toluenesulfonate, benzenesulfonate,4-(4-toluenesulfonyloxy)benzenesulfonate, naphthalenesulfonate,camphorsulfonate, octanesulfonate, dodecylbenzenesulfonate,butanesulfonate, and methanesulfonate. Iodonium salts based oncombination of the foregoing examples are included.

[0212] Exemplary sulfonyldiazomethane compounds includebissulfonyldiazomethane compounds and sulfonyl-carbonyldiazomethanecompounds such as bis(ethylsulfonyl)diazomethane,bis(1-methylpropylsulfonyl)diazomethane,bis(2-methylpropylsulfonyl)diazomethane,bis(1,1-dimethylethylsulfonyl)diazomethane,bis(cyclohexylsulfonyl)diazomethane,bis(perfluoroisopropylsulfonyl)diazomethane,bis(phenylsulfonyl)diazomethane,bis(4-methylphenylsulfonyl)diazomethane,bis(2,4-dimethylphenylsulfonyl)diazomethane,bis(2-naphthylsulfonyl)diazomethane,bis(4-acetyloxyphenylsulfonyl)diazomethane,bis(4-methanesulfonyloxyphenylsulfonyl)diazomethane,bis(4-(4-toluenesulfonyloxy)phenylsulfonyl)diazomethane,4-methylphenylsulfonylbenzoyldiazomethane,tert-butylcarbonyl-4-methylphenylsulfonyldiazomethane,2-naphthylsulfonylbenzoyldiazomethane,4-methylphenylsulfonyl-2-naphthoyldiazomethane,methylsulfonylbenzoyldiazomethane, andtert-butoxycarbonyl-4-methylphenylsulfonyldiazomethane.

[0213] N-sulfonyloxyimide photoacid generators include combinations ofimide skeletons with sulfonates. Exemplary imide skeletons aresuccinimide, naphthalene dicarboxylic acid imide, phthalimide,cyclohexyldicarboxylic acid imide, 5-norbornene-2,3-dicarboxylic acidimide, and 7-oxabicyclo[2.2.1]-5-heptene-2,3-dicarboxylic acid imide.Exemplary sulfonates include trifluoromethanesulfonate,nonafluorobutanesulfonate, heptadecafluorooctanesulfonate,2,2,2-trifluoroethanesulfonate, pentafluorobenzenesulfonate,4-trifluoromethylbenzenesulfonate, 4-fluorobenzenesulfonate,mesitylenesulfonate, 2,4,6-triisopropylbenzenesulfonate,toluenesulfonate, benzenesulfonate, naphthalenesulfonate,camphorsulfonate, octanesulfonate, dodecylbenzenesulfonate,butanesulfonate, and methanesulfonate.

[0214] Benzoinsulfonate photoacid generators include benzoin tosylate,benzoin mesylate, and benzoin butanesulfonate.

[0215] Pyrogallol trisulfonate photoacid generators include pyrogallol,fluoroglycine, catechol, resorcinol, hydroquinone, in which all thehydroxyl groups are substituted with trifluoromethanesulfonate,nonafluorobutanesulfonate, heptadecafluorooctanesulfonate,2,2,2-trifluoroethanesulfonate, pentafluorobenzenesulfonate,4-trifluoromethylbenzenesulfonate, 4-fluorobenzenesulfonate,toluenesulfonate, benzenesulfonate, naphthalenesulfonate,camphorsulfonate, octanesulfonate, dodecylbenzenesulfonate,butanesulfonate, and methanesulfonate.

[0216] Nitrobenzyl sulfonate photoacid generators include2,4-dinitrobenzyl sulfonate, 2-nitrobenzyl sulfonate, and2,6-dinitrobenzyl sulfonate, with exemplary sulfonates includingtrifluoromethanesulfonate, nonafluorobutanesulfonate,heptadecafluorooctanesulfonate, 2,2,2-trifluoroethanesulfonate,pentafluorobenzenesulfonate, 4-trifluoromethylbenzenesulfonate,4-fluorobenzenesulfonate, toluenesulfonate, benzenesulfonate,naphthalenesulfonate, camphorsulfonate, octanesulfonate,dodecylbenzenesulfonate, butanesulfonate, and methanesulfonate. Alsouseful are analogous nitrobenzyl sulfonate compounds in which the nitrogroup on the benzyl side is substituted with a trifluoromethyl group.

[0217] Sulfone photoacid generators include

[0218] bis(phenylsulfonyl)methane,

[0219] bis(4-methylphenylsulfonyl)methane,

[0220] bis(2-naphthylsulfonyl)methane,

[0221] 2,2-bis(phenylsulfonyl)propane,

[0222] 2,2-bis(4-methylphenylsulfonyl)propane,

[0223] 2,2-bis(2-naphthylsulfonyl)propane,

[0224] 2-methyl-2-(p-toluenesulfonyl)propiophenone,

[0225] 2-cyclohexylcarbonyl-2-(p-toluenesulfonyl)propane, and

[0226] 2,4-dimethyl-2-(p-toluenesulfonyl)pentan-3-one.

[0227] Photoacid generators in the form of glyoxime derivatives aredescribed in Japanese Patent No. 2,906,999 and JP-A 9-301948 and include

[0228] bis-O-(p-toluenesulfonyl)-α-dimethylglyoxime,

[0229] bis-O-(p-toluenesulfonyl)-α-diphenylglyoxime,

[0230] bis-O-(p-toluenesulfonyl)-α-dicyclohexylglyoxime,

[0231] bis-O-(p-toluenesulfonyl)-2,3-pentanedioneglyoxime,

[0232] bis-O-(n-butanesulfonyl)-α-dimethylglyoxime,

[0233] bis-O-(n-butanesulfonyl)-α-diphenylglyoxime,

[0234] bis-O-(n-butanesulfonyl)-α-dicyclohexylglyoxime,

[0235] bis-O-(methanesulfonyl)-α-dimethylglyoxime,

[0236] bis-O-(trifluoromethanesulfonyl)-α-dimethylglyoxime,

[0237] bis-O-(2,2,2-trifluoroethanesulfonyl)-α-dimethylglyoxime,

[0238] bis-O-(10-camphorsulfonyl)-α-dimethylglyoxime,

[0239] bis-O-(benzenesulfonyl)-α-dimethylglyoxime,

[0240] bis-O-(p-fluorobenzenesulfonyl)-α-dimethylglyoxime,

[0241] bis-O-(p-trifluoromethylbenzenesulfonyl)-α-dimethylglyoxime,

[0242] bis-O-(xylenesulfonyl)-α-dimethylglyoxime,

[0243] bis-O-(trifluoromethanesulfonyl)-nioxime,

[0244] bis-O-(2,2,2-trifluoroethanesulfonyl)-nioxime,

[0245] bis-O-(10-camphorsulfonyl)-nioxime,

[0246] bis-O-(benzenesulfonyl)-nioxime,

[0247] bis-O-(p-fluorobenzenesulfonyl)-nioxime,

[0248] bis-O-(p-trifluoromethylbenzenesulfonyl)-nioxime, and

[0249] bis-O-(xylenesulfonyl)-nioxime.

[0250] Also included are the oxime sulfonates described in U.S. Pat. No.6,004,724, for example,

[0251](5-(4-toluenesulfonyl)oxyimino-5H-thiophen-2-ylidene)phenylacetonitrile,

[0252](5-(10-camphorsulfonyl)oxyimino-5H-thiophen-2-ylidene)phenylacetonitrile,

[0253](5-n-octanesulfonyloxyimino-5H-thiophen-2-ylidene)phenylacetonitrile,

[0254](5-(4-toluenesulfonyl)oxyimino-5H-thiophen-2-ylidene)(2-methylphenyl)acetonitrile,

[0255](5-(10-camphorsulfonyl)oxyimino-5H-thiophen-2-ylidene)(2-methylphenyl)acetonitrile,

[0256](5-n-octanesulfonyloxyimino-5H-thiophen-2-ylidene)(2-methylphenyl)acetonitrile,etc.

[0257] Also included are the oxime sulfonates described in U.S. Pat. No.6,261,738 and JP-A 2000-314956, for example,

[0258] 2,2,2-trifluoro-1-phenyl-ethanone oxime-O-methylsulfonate;

[0259] 2,2,2-trifluoro-1-phenyl-ethanoneoxime-O-(10-camphorylsulfonate);

[0260] 2,2,2-trifluoro-1-phenyl-ethanoneoxime-O-(4-methoxyphenylsulfonate);

[0261] 2,2,2-trifluoro-1-phenyl-ethanone oxime-O-(1-naphthylsulfonate);

[0262] 2,2,2-trifluoro-1-phenyl-ethanone oxime-O-(2-naphthylsulfonate);

[0263] 2,2,2-trifluoro-1-phenyl-ethanoneoxime-O-(2,4,6-trimethylphenylsulfonate);

[0264] 2,2,2-trifluoro-1-(4-methylphenyl)-ethanoneoxime-O-(10-camphorylsulfonate);

[0265] 2,2,2-trifluoro-1-(4-methylphenyl)-ethanoneoxime-O-(methylsulfonate);

[0266] 2,2,2-trifluoro-1-(2-methylphenyl)-ethanoneoxime-O-(10-camphorylsulfonate);

[0267] 2,2,2-trifluoro-1-(2,4-dimethylphenyl)-ethanoneoxime-O-(10-camphorylsulfonate);

[0268] 2,2,2-trifluoro-1-(2,4-dimethylphenyl)-ethanoneoxime-O-(1-naphthylsulfonate);

[0269] 2,2,2-trifluoro-1-(2,4-dimethylphenyl)-ethanoneoxime-O-(2-naphthylsulfonate);

[0270] 2,2,2-trifluoro-1-(2,4,6-trimethylphenyl)-ethanoneoxime-O-(10-camphorylsulfonate);

[0271] 2,2,2-trifluoro-1-(2,4,6-trimethylphenyl)-ethanoneoxime-O-(1-naphthylsulfonate);

[0272] 2,2,2-trifluoro-1-(2,4,6-trimethylphenyl)-ethanoneoxime-O-(2-naphthylsulfonate);

[0273] 2,2,2-trifluoro-1-(4-methoxyphenyl)-ethanoneoxime-O-methylsulfonate;

[0274] 2,2,2-trifluoro-1-(4-methylthiophenyl)-ethanoneoxime-O-methylsulfonate;

[0275] 2,2,2-trifluoro-1-(3,4-dimethoxyphenyl)-ethanoneoxime-O-methylsulfonate;

[0276] 2,2,3,3,4,4,4-heptafluoro-1-phenyl-butanoneoxime-O-(10-camphorylsulfonate);

[0277] 2,2,2-trifluoro-1-(phenyl)-ethanone oxime-O-methylsulfonate;

[0278] 2,2,2-trifluoro-1-(phenyl)-ethanoneoxime-O-10-camphorylsulfonate;

[0279] 2,2,2-trifluoro-1-(phenyl)-ethanoneoxime-O-(4-methoxyphenyl)sulfonate;

[0280] 2,2,2-trifluoro-1-(phenyl)-ethanoneoxime-O-(1-naphthyl)sulfonate;

[0281] 2,2,2-trifluoro-1-(phenyl)-ethanoneoxime-O-(2-naphthyl)sulfonate;

[0282] 2,2,2-trifluoro-1-(phenyl)-ethanoneoxime-O-(2,4,6-trimethylphenyl)sulfonate;

[0283] 2,2,2-trifluoro-1-(4-methylphenyl)-ethanoneoxime-O-(10-camphoryl)sulfonate;

[0284] 2,2,2-trifluoro-1-(4-methylphenyl)-ethanoneoxime-O-methylsulfonate;

[0285] 2,2,2-trifluoro-1-(2-methylphenyl)-ethanoneoxime-O-(10-camphoryl)sulfonate;

[0286] 2,2,2-trifluoro-1-(2,4-dimethylphenyl)-ethanoneoxime-O-(1-naphthyl)sulfonate;

[0287] 2,2,2-trifluoro-1-(2,4-dimethylphenyl)-ethanoneoxime-O-(2-naphthyl)sulfonate;

[0288] 2,2,2-trifluoro-1-(2,4,6-trimethylphenyl)-ethanoneoxime-O-(10-camphoryl)sulfonate;

[0289] 2,2,2-trifluoro-1-(2,4,6-trimethylphenyl)-ethanoneoxime-O-(1-naphthyl)sulfonate;

[0290] 2,2,2-trifluoro-1-(2,4,6-trimethylphenyl)-ethanoneoxime-O-(2-naphthyl)sulfonate;

[0291] 2,2,2-trifluoro-1-(4-methoxyphenyl)-ethanoneoxime-O-methylsulfonate;

[0292] 2,2,2-trifluoro-1-(4-thiomethylphenyl)-ethanoneoxime-O-methylsulfonate;

[0293] 2,2,2-trifluoro-1-(3,4-dimethoxyphenyl)-ethanoneoxime-O-methylsulfonate;

[0294] 2,2,2-trifluoro-1-(4-methoxyphenyl)-ethanoneoxime-O-(4-methylphenyl)sulfonate;

[0295] 2,2,2-trifluoro-1-(4-methoxyphenyl)-ethanoneoxime-O-(4-methoxyphenyl)sulfonate;

[0296] 2,2,2-trifluoro-1-(4-methoxyphenyl)-ethanoneoxime-O-(4-dodecylphenyl)sulfonate;

[0297] 2,2,2-trifluoro-1-(4-methoxyphenyl)-ethanoneoxime-O-octylsulfonate;

[0298] 2,2,2-trifluoro-1-(4-thiomethylphenyl)-ethanoneoxime-O-(4-methoxyphenyl)sulfonate;

[0299] 2,2,2-trifluoro-1-(4-thiomethylphenyl)-ethanoneoxime-O-(4-dodecylphenyl)sulfonate;

[0300] 2,2,2-trifluoro-1-(4-thiomethylphenyl)-ethanoneoxime-O-octylsulfonate;

[0301] 2,2,2-trifluoro-1-(4-thiomethylphenyl)-ethanoneoxime-O-(2-naphthyl)sulfonate;

[0302] 2,2,2-trifluoro-1-(2-methylphenyl)-ethanoneoxime-O-methylsulfonate;

[0303] 2,2,2-trifluoro-1-(4-methylphenyl)-ethanoneoxime-O-phenylsulfonate;

[0304] 2,2,2-trifluoro-1-(4-chlorophenyl)-ethanoneoxime-O-phenylsulfonate;

[0305] 2,2,3,3,4,4,4-heptafluoro-1-(phenyl)-butanoneoxime-O-(10-camphoryl)sulfonate;

[0306] 2,2,2-trifluoro-1-naphthyl-ethanone oxime-O-methylsulfonate;

[0307] 2,2,2-trifluoro-2-naphthyl-ethanone oxime-O-methylsulfonate;

[0308] 2,2,2-trifluoro-1-[4-benzylphenyl]-ethanoneoxime-O-methylsulfonate;

[0309] 2,2,2-trifluoro-1-[4-(phenyl-1,4-dioxa-but-1-yl)phenyl]-ethanoneoxime-O-methylsulfonate;

[0310] 2,2,2-trifluoro-1-naphthyl-ethanone oxime-O-propylsulfonate;

[0311] 2,2,2-trifluoro-2-naphthyl-ethanone oxime-O-propylsulfonate;

[0312] 2,2,2-trifluoro-1-[4-benzylphenyl]-ethanoneoxime-O-propylsulfonate;

[0313] 2,2,2-trifluoro-1-[4-methylsulfonylphenyl]-ethanoneoxime-O-propylsulfonate;

[0314] 1,3-bis[1-(4-phenoxyphenyl)-2,2,2-trifluoroethanoneoxime-O-sulfonyl]phenyl;

[0315] 2,2,2-trifluoro-1-[4-methylsulfonyloxyphenyl]-ethanoneoxime-O-propylsulfonate;

[0316] 2,2,2-trifluoro-1-[4-methylcarbonyloxyphenyl]-ethanoneoxime-O-propylsulfonate;

[0317] 2,2,2-trifluoro-1-[6H,7H-5,8-dioxonaphth-2-yl]-ethanoneoxime-O-propylsulfonate;

[0318] 2,2,2-trifluoro-1-[4-methoxycarbonylmethoxyphenyl]-ethanoneoxime-O-propylsulfonate;

[0319]2,2,2-trifluoro-1-[4-(methoxycarbonyl)-(4-amino-1-oxa-pent-1-yl)-phenyl]-ethanoneoxime-O-propylsulfonate;

[0320] 2,2,2-trifluoro-1-[3,5-dimethyl-4-ethoxyphenyl]-ethanoneoxime-O-propylsulfonate;

[0321] 2,2,2-trifluoro-1-[4-benzyloxyphenyl]-ethanoneoxime-O-propylsulfonate;

[0322] 2,2,2-trifluoro-1-[2-thiophenyl]-ethanoneoxime-O-propylsulfonate; and

[0323] 2,2,2-trifluoro-1-[1-dioxa-thiophen-2-yl)]-ethanoneoxime-O-propylsulfonate.

[0324] Also included are the oxime sulfonates described in JP-A 9-95479and JP-A 9-230588 and the references cited therein, for example,

[0325] α-(p-toluenesulfonyloxyimino)-phenylacetonitrile,

[0326] α-(p-chlorobenzenesulfonyloxyimino)-phenylacetonitrile,

[0327] α-(4-nitrobenzenesulfonyloxyimino)-phenylacetonitrile,

[0328]α-(4-nitro-2-trifluoromethylbenzenesulfonyloxyimino)phenylacetonitrile,

[0329] α-(benzenesulfonyloxyimino)-4-chlorophenylacetonitrile,

[0330] α-(benzenesulfonyloxyimino)-2,4-dichlorophenylacetonitrile,

[0331] α-(benzenesulfonyloxyimino)-2,6-dichlorophenylacetonitrile,

[0332] α-(benzenesulfonyloxyimino)-4-methoxyphenylacetonitrile,

[0333] α-(2-chlorobenzenesulfonyloxyimino)-4-methoxyphenylacetonitrile,

[0334] α-(benzenesulfonyloxyimino)-2-thienylacetonitrile,

[0335] α-(4-dodecylbenzenesulfonyloxyimino)-phenylacetonitrile,

[0336] α-[(4-toluenesulfonyloxyimino)-4-methoxyphenyl]acetonitrile,

[0337] α-[(dodecylbenzenesulfonyloxyimino)-4-methoxyphenyl]acetonitrile,

[0338] α-(tosyloxyimino)-3-thienylacetonitrile,

[0339] α-(methylsulfonyloxyimino)-1-cyclopentenylacetonitrile,

[0340] α-(ethylsulfonyloxyimino)-1-cyclopentenylacetonitrile,

[0341] α-(isopropylsulfonyloxyimino)-1-cyclopentenylacetonitrile,

[0342] α-(n-butylsulfonyloxyimino)-1-cyclopentenylacetonitrile,

[0343] α-(ethylsulfonyloxyimino)-1-cyclohexenylacetonitrile,

[0344] α-(isopropylsulfonyloxyimino)-1-cyclohexenylacetonitrile, and

[0345] α-(n-butylsulfonyloxyimino)-1-cyclohexenylacetonitrile.

[0346] Suitable bisoxime sulfonates include those described in JP-A9-208554, for example,

[0347] bis(α-(4-toluenesulfonyloxy)imino)-p-phenylenediacetonitrile,

[0348] bis(α-(benzenesulfonyloxy)imino)-p-phenylenediacetonitrile,

[0349] bis(α-(methanesulfonyloxy)imino)-p-phenylenediacetonitrile,

[0350] bis(α-(butanesulfonyloxy)imino)-p-phenylenediacetonitrile,

[0351] bis(α-(10-camphorsulfonyloxy)imino)-p-phenylenediacetonitrile,

[0352] bis(α-(4-toluenesulfonyloxy)imino)-p-phenylenediacetonitrile,

[0353]bis(α-(trifluoromethanesulfonyloxy)imino)-p-phenylenediacetonitrile,

[0354]bis(α-(4-methoxybenzenesulfonyloxy)imino)-p-phenylenediacetonitrile,

[0355] bis(α-(4-toluenesulfonyloxy)imino)-m-phenylenediacetonitrile,

[0356] bis(α-(benzenesulfonyloxy)imino)-m-phenylenediacetonitrile,

[0357] bis(α-(methanesulfonyloxy)imino)-m-phenylenediacetonitrile,

[0358] bis(α-(butanesulfonyloxy)imino)-m-phenylenediacetonitrile,

[0359] bis(α-(10-camphorsulfonyloxy)imino)-m-phenylenediacetonitrile,

[0360] bis(α-(4-toluenesulfonyloxy)imino)-m-phenylenediacetonitrile,

[0361]bis(α-(trifluoromethanesulfonyloxy)imino)-m-phenylenediacetonitrile,

[0362]bis(α-(4-methoxybenzenesulfonyloxy)imino)-m-phenylenediacetonitrile,etc.

[0363] Of these, preferred photoacid generators are sulfonium salts,bissulfonyldiazomethanes, N-sulfonyloxyimides and glyoxime derivatives.More preferred photoacid generators are sulfonium salts,bissulfonyldiazomethanes, and N-sulfonyloxyimides. Typical examplesinclude triphenylsulfonium p-toluenesulfonate, triphenylsulfoniumcamphorsulfonate, triphenylsulfonium pentafluorobenzenesulfonate,triphenylsulfonium nonafluorobutanesulfonate, triphenylsulfonium4-(4′-toluenesulfonyloxy)benzenesulfonate, triphenylsulfonium2,4,6-triisopropylbenzenesulfonate, 4-tert-butoxyphenyldiphenylsulfoniump-toluenesulfonate, 4-tert-butoxyphenyldiphenylsulfoniumcamphorsulfonate, 4-tert-butoxyphenyldiphenylsulfonium4-(4′-toluenesulfonyloxy)benzenesulfonate, tris(4-methylphenyl)sulfoniumcamphorsulfonate, tris(4-tert-butylphenyl)sulfonium camphorsulfonate,bis(tert-butylsulfonyl)diazomethane,bis(cyclohexylsulfonyl)diazomethane,bis(2,4-dimethylphenylsulfonyl)diazomethane,bis(4-tert-butylphenylsulfonyl)diazomethane,N-camphorsulfonyloxy-5-norbornene-2,3-carboxylic acid imide, andN-p-toluenesulfonyloxy-5-norbornene-2,3-carboxylic acid imide.

[0364] In the resist composition comprising the sulfonyldiazomethane offormula (1) or (1a) as the first photoacid generator according to theinvention, the second photoacid generator (C) may be used in any desiredamount as long as it does not compromise the effects of thesulfonyldiazomethane of formula (1) or (1a). An appropriate amount ofthe second photoacid generator (C) is 0 to 10 parts, and especially 0 to5 parts by weight per 100 parts by weight of the solids in thecomposition. Too high a proportion of the second photoacid generator (C)may give rise to problems of degraded resolution and foreign matter upondevelopment and resist film peeling. The second photoacid generators maybe used alone or in admixture of two or more. The transmittance of theresist film can be controlled by using a (second) photoacid generatorhaving a low transmittance at the exposure wavelength and adjusting theamount of the photoacid generator added.

[0365] In the resist composition comprising the sulfonyldiazomethane asthe photoacid generator according to the invention, there may be added acompound which is decomposed with an acid to generate an acid, that is,acid-propagating compound. For these compounds, reference should be madeto J. Photopolym. Sci. and Tech., 8, 43-44, 45-46 (1995), and ibid., 9,29-30 (1996).

[0366] Examples of the acid-propagating compound includetert-butyl-2-methyl-2-tosyloxymethyl acetoacetate and2-phenyl-2-(2-tosyloxyethyl)-1,3-dioxolane, but are not limited thereto.Of well-known photoacid generators, many of those compounds having poorstability, especially poor thermal stability exhibit an acid-propagatingcompound-like behavior.

[0367] In the resist composition comprising the sulfonyldiazomethane asthe photoacid generator according to the invention, an appropriateamount of the acid-propagating compound is up to 2 parts, and especiallyup to 1 part by weight per 100 parts by weight of the solids in thecomposition. Excessive amounts of the acid-propagating compound makediffusion control difficult, leading to degradation of resolution andpattern configuration.

[0368] Component (D)

[0369] The basic compound used as component (D) is preferably a compoundcapable of suppressing the rate of diffusion when the acid generated bythe photoacid generator diffuses within the resist film. The inclusionof this type of basic compound holds down the rate of acid diffusionwithin the resist film, resulting in better resolution. In addition, itsuppresses changes in sensitivity following exposure and reducessubstrate and environment dependence, as well as improving the exposurelatitude and the pattern profile.

[0370] Examples of basic compounds include primary, secondary, andtertiary aliphatic amines, mixed amines, aromatic amines, heterocyclicamines, carboxyl group-bearing nitrogenous compounds, sulfonylgroup-bearing nitrogenous compounds, hydroxyl group-bearing nitrogenouscompounds, hydroxyphenyl group-bearing nitrogenous compounds, alcoholicnitrogenous compounds, amide derivatives, and imide derivatives.

[0371] Examples of suitable primary aliphatic amines include ammonia,methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine,isobutylamine, sec-butylamine, tert-butylamine, pentylamine,tert-amylamine, cyclopentylamine, hexylamine, cyclohexylamine,heptylamine, octylamine, nonylamine, decylamine, dodecylamine,cetylamine, methylenediamine, ethylenediamine, andtetraethylenepentamine. Examples of suitable secondary aliphatic aminesinclude dimethylamine, diethylamine, di-n-propylamine, diisopropylamine,di-n-butylamine, diisobutylamine, di-sec-butylamine, dipentylamine,dicyclopentylamine, dihexylamine, dicyclohexylamine, diheptylamine,dioctylamine, dinonylamine, didecylamine, didodecylamine, dicetylamine,N,N-dimethylmethylenediamine, N,N-dimethylethylenediamine, andN,N-dimethyltetraethylenepentamine. Examples of suitable tertiaryaliphatic amines include trimethylamine, triethylamine,tri-n-propylamine, triisopropylamine, tri-n-butylamine,triisobutylamine, tri-sec-butylamine, tripentylamine,tricyclopentylamine, trihexylamine, tricyclohexylamine, triheptylamine,trioctylamine, trinonylamine, tridecylamine, tridodecylamine,tricetylamine, N,N,N′,N′-tetramethylmethylenediamine,N,N,N′,N′-tetramethylethylenediamine, andN,N,N′,N′-tetramethyltetraethylenepentamine.

[0372] Examples of suitable mixed amines include dimethylethylamine,methylethylpropylamine, benzylamine, phenethylamine, andbenzyldimethylamine. Examples of suitable aromatic and heterocyclicamines include aniline derivatives (e.g., aniline, N-methylaniline,N-ethylaniline, N-propylaniline, N,N-dimethylaniline, 2-methylaniline,3-methylaniline, 4-methylaniline, ethylaniline, propylaniline,trimethylaniline, 2-nitroaniline, 3-nitroaniline, 4-nitroaniline,2,4-dinitroaniline, 2,6-dinitroaniline, 3,5-dinitroaniline, andN,N-dimethyltoluidine), diphenyl(p-tolyl)amine, methyldiphenylamine,triphenylamine, phenylenediamine, naphthylamine, diaminonaphthalene,pyrrole derivatives (e.g., pyrrole, 2H-pyrrole, 1-methylpyrrole,2,4-dimethylpyrrole, 2,5-dimethylpyrrole, and N-methylpyrrole), oxazolederivatives (e.g., oxazole and isooxazole), thiazole derivatives (e.g.,thiazole and isothiazole), imidazole derivatives (e.g., imidazole,4-methylimidazole, and 4-methyl-2-phenylimidazole), pyrazolederivatives, furazan derivatives, pyrroline derivatives (e.g., pyrrolineand 2-methyl-1-pyrroline), pyrrolidine derivatives (e.g., pyrrolidine,N-methylpyrrolidine, pyrrolidinone, and N-methylpyrrolidone),imidazoline derivatives, imidazolidine derivatives, pyridine derivatives(e.g., pyridine, methylpyridine, ethylpyridine, propylpyridine,butylpyridine, 4-(1-butylpentyl)pyridine, dimethylpyridine,trimethylpyridine, triethylpyridine, phenylpyridine,3-methyl-2-phenylpyridine, 4-tert-butylpyridine, diphenylpyridine,benzylpyridine, methoxypyridine, butoxypyridine, dimethoxypyridine,1-methyl-2-pyridone, 4-pyrrolidinopyridine, 1-methyl-4-phenylpyridine,2-(1-ethylpropyl)pyridine, aminopyridine, and dimethylaminopyridine),pyridazine derivatives, pyrimidine derivatives, pyrazine derivatives,pyrazoline derivatives, pyrazolidine derivatives, piperidinederivatives, piperazine derivatives, morpholine derivatives, indolederivatives, isoindole derivatives, 1H-indazole derivatives, indolinederivatives, quinoline derivatives (e.g., quinoline and3-quinolinecarbonitrile), isoquinoline derivatives, cinnolinederivatives, quinazoline derivatives, quinoxaline derivatives,phthalazine derivatives, purine derivatives, pteridine derivatives,carbazole derivatives, phenanthridine derivatives, acridine derivatives,phenazine derivatives, 1,10-phenanthroline derivatives, adeninederivatives, adenosine derivatives, guanine derivatives, guanosinederivatives, uracil derivatives, and uridine derivatives.

[0373] Examples of suitable carboxyl group-bearing nitrogenous compoundsinclude aminobenzoic acid, indolecarboxylic acid, and amino acidderivatives (e.g. nicotinic acid, alanine, alginine, aspartic acid,glutamic acid, glycine, histidine, isoleucine, glycylleucine, leucine,methionine, phenylalanine, threonine, lysine,3-aminopyrazine-2-carboxylic acid, and methoxyalanine). Examples ofsuitable sulfonyl group-bearing nitrogenous compounds include3-pyridinesulfonic acid and pyridinium p-toluenesulfonate. Examples ofsuitable hydroxyl group-bearing nitrogenous compounds, hydroxyphenylgroup-bearing nitrogenous compounds, and alcoholic nitrogenous compoundsinclude 2-hydroxypyridine, aminocresol, 2,4-quinolinediol,3-indolemethanol hydrate, monoethanolamine, diethanolamine,triethanolamine, N-ethyldiethanolamine, N,N-diethylethanolamine,triisopropanolamine, 2,2′-iminodiethanol, 2-aminoethanol,3-amino-1-propanol, 4-amino-1-butanol, 4-(2-hydroxyethyl)morpholine,2-(2-hydroxyethyl)pyridine, 1-(2-hydroxyethyl)piperazine,1-[2-(2-hydroxyethoxy)ethyl]piperazine, piperidine ethanol,1-(2-hydroxyethyl)pyrrolidine, 1-(2-hydroxyethyl)-2-pyrrolidinone,3-piperidino-1,2-propanediol, 3-pyrrolidino-1,2-propanediol,8-hydroxyjulolidine, 3-quinuclidinol, 3-tropanol, 1-methyl-2-pyrrolidineethanol, 1-aziridine ethanol, N-(2-hydroxyethyl)phthalimide, andN-(2-hydroxyethyl)isonicotinamide. Examples of suitable amidederivatives include formamide, N-methylformamide, N,N-dimethylformamide,acetamide, N-methylacetamide, N,N-dimethylacetamide, propionamide, andbenzamide. Suitable imide derivatives include phthalimide, succinimide,and maleimide.

[0374] In addition, basic compounds of the following general formula(D1) may also be included alone or in admixture.

N(X′)_(w)(Y)_(3-w)  (D1)

[0375] In the formula, w is equal to 1, 2 or 3; Y is independentlyhydrogen or a straight, branched or cyclic alkyl group of 1 to 20 carbonatoms which may contain a hydroxyl group or ether structure; and X′ isindependently selected from groups of the following general formulas(X′1) to (X′3), and two or three X′ may bond together to form a ring.

[0376] In the formulas, R³⁰⁰, R³⁰² and R³⁰⁵ are independently straightor branched alkylene groups of 1 to 4 carbon atoms; R³⁰¹, R³⁰⁴ and R³⁰⁶are independently hydrogen, straight, branched or cyclic alkyl groups of1 to 20 carbon atoms, which may contain at least one hydroxyl group,ether structure, ester structure or lactone ring; and R³⁰³ is a singlebond or a straight or branched alkylene group of 1 to 4 carbon atoms.

[0377] Illustrative examples of the basic compounds of formula (D1)include tris(2-methoxymethoxyethyl)amine,tris{2-(2-methoxyethoxy)ethyl}amine,tris{2-(2-methoxyethoxymethoxy)ethyl}amine,tris{2-(1-methoxyethoxy)ethyl}amine, tris{2-(1-ethoxyethoxy)ethyl}amine,tris{2-(1-ethoxypropoxy)ethyl}amine,tris[2-{2-(2-hydroxyethoxy)ethoxy}ethyl]amine,4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane,4,7,13,18-tetraoxa-1,10-diazabicyclo[8.5.5]eicosane,1,4,10,13-tetraoxa-7,16-diazabicyclooctadecane,1-aza-12-crown-4,1-aza-15-crown-5,1-aza-18-crown-6,tris(2-formyloxyethyl)amine, tris(2-acetoxyethyl)amine,tris(2-propionyloxyethyl)amine, tris(2-butyryloxyethyl)amine,tris(2-isobutyryloxyethyl)amine, tris(2-valeryloxyethyl)amine,tris(2-pivaloyloxyethyl)amine,N,N-bis(2-acetoxyethyl)-2-(acetoxyacetoxy)ethylamine,tris(2-methoxycarbonyloxyethyl)amine,tris(2-tert-butoxycarbonyloxyethyl)amine,tris[2-(2-oxopropoxy)ethyl]amine,tris[2-(methoxycarbonylmethyl)oxyethyl]amine,tris[2-(tert-butoxycarbonylmethyloxy)ethyl]amine,tris[2-(cyclohexyloxycarbonylmethyloxy)ethyl]amine,tris(2-methoxycarbonylethyl)amine, tris(2-ethoxycarbonylethyl)amine,N,N-bis(2-hydroxyethyl)-2-(methoxycarbonyl)ethylamine,N,N-bis(2-acetoxyethyl)-2-(methoxycarbonyl)ethylamine,N,N-bis(2-hydroxyethyl)-2-(ethoxycarbonyl)ethylamine,N,N-bis(2-acetoxyethyl)-2-(ethoxycarbonyl)ethylamine,N,N-bis(2-hydroxyethyl)-2-(2-methoxyethoxycarbonyl)ethylamine,N,N-bis(2-acetoxyethyl)-2-(2-methoxyethoxycarbonyl)ethylamine,N,N-bis(2-hydroxyethyl)-2-(2-hydroxyethoxycarbonyl)ethylamine,N,N-bis(2-acetoxyethyl)-2-(2-acetoxyethoxycarbonyl)ethylamine,N,N-bis(2-hydroxyethyl)-2-[(methoxycarbonyl)methoxycarbonyl]-ethylamine,N,N-bis(2-acetoxyethyl)-2-[(methoxycarbonyl)methoxycarbonyl]-ethylamine,N,N-bis(2-hydroxyethyl)-2-(2-oxopropoxycarbonyl)ethylamine,N,N-bis(2-acetoxyethyl)-2-(2-oxopropoxycarbonyl)ethylamine,N,N-bis(2-hydroxyethyl)-2-(tetrahydrofurfuryloxycarbonyl)ethylamine,N,N-bis(2-acetoxyethyl)-2-(tetrahydrofurfuryloxycarbonyl)ethylamine,N,N-bis(2-hydroxyethyl)-2-[(2-oxotetrahydrofuran-3-yl)oxycarbonyl]ethylamine,N,N-bis(2-acetoxyethyl)-2-[(2-oxotetrahydrofuran-3-yl)oxycarbonyl]ethylamine,N,N-bis(2-hydroxyethyl)-2-(4-hydroxybutoxycarbonyl)ethylamine,N,N-bis(2-formyloxyethyl)-2-(4-formyloxybutoxycarbonyl)ethylamine,N,N-bis(2-formyloxyethyl)-2-(2-formyloxyethoxycarbonyl)ethylamine,N,N-bis(2-methoxyethyl)-2-(methoxycarbonyl)ethylamine,N-(2-hydroxyethyl)-bis[2-(methoxycarbonyl)ethyl]amine,N-(2-acetoxyethyl)-bis[2-(methoxycarbonyl)ethyl]amine,N-(2-hydroxyethyl)-bis[2-(ethoxycarbonyl)ethyl]amine,N-(2-acetoxyethyl)-bis[2-(ethoxycarbonyl)ethyl]amine,N-(3-hydroxy-1-propyl)-bis[2-(methoxycarbonyl)ethyl]amine,N-(3-acetoxy-1-propyl)-bis[2-(methoxycarbonyl)ethyl]amine,N-(2-methoxyethyl)-bis[2-(methoxycarbonyl)ethyl]amine,N-butyl-bis[2-(methoxycarbonyl)ethyl]amine,N-butyl-bis[2-(2-methoxyethoxycarbonyl)ethyl]amine,N-methyl-bis(2-acetoxyethyl)amine, N-ethyl-bis(2-acetoxyethyl)amine,N-methyl-bis(2-pivaloyloxyethyl)amine,N-ethyl-bis[2-(methoxycarbonyloxy)ethyl]amine,N-ethyl-bis[2-(tert-butoxycarbonyloxy)ethyl]amine,tris(methoxycarbonylmethyl)amine, tris(ethoxycarbonylmethyl)amine,N-butyl-bis(methoxycarbonylmethyl)amine,N-hexyl-bis(methoxycarbonylmethyl)amine, andβ-(diethylamino)-δ-valerolactone.

[0378] Also useful are one or more of cyclic structure-bearing basiccompounds having the following general formula (D2).

[0379] Herein X′ is as defined above, and R³⁰⁷ is a straight or branchedalkylene group of 2 to 20 carbon atoms which may contain one or morecarbonyl groups, ether structures, ester structures or sulfidestructures.

[0380] Illustrative examples of the cyclic structure-bearing basiccompounds having formula (D2) include1-[2-(methoxymethoxy)ethyl]pyrrolidine,1-[2-(methoxymethoxy)ethyl]piperidine,4-[2-(methoxymethoxy)ethyl]morpholine,1-[2-[(2-methoxyethoxy)methoxy]ethyl]pyrrolidine,1-[2-[(2-methoxyethoxy)methoxy]ethyl]piperidine,4-[2-[(2-methoxyethoxy)methoxy]ethyl]morpholine, 2-(1-pyrrolidinyl)ethylacetate, 2-piperidinoethyl acetate, 2-morpholinoethyl acetate,2-(1-pyrrolidinyl)ethyl formate, 2-piperidinoethyl propionate,2-morpholinoethyl acetoxyacetate, 2-(1-pyrrolidinyl)ethylmethoxyacetate, 4-[2-(methoxycarbonyloxy)ethyl]morpholine,1-[2-(t-butoxycarbonyloxy)ethyl]piperidine,4-[2-(2-methoxyethoxycarbonyloxy)ethyl]morpholine, methyl3-(1-pyrrolidinyl)propionate, methyl 3-piperidinopropionate, methyl3-morpholinopropionate, methyl 3-(thiomorpholino)propionate, methyl2-methyl-3-(1-pyrrolidinyl)propionate, ethyl 3-morpholinopropionate,methoxycarbonylmethyl 3-piperidinopropionate, 2-hydroxyethyl3-(1-pyrrolidinyl)propionate, 2-acetoxyethyl 3-morpholinopropionate,2-oxotetrahydrofuran-3-yl 3-(1-pyrrolidinyl)propionate,tetrahydrofurfuryl 3-morpholinopropionate, glycidyl3-piperidinopropionate, 2-methoxyethyl 3-morpholinopropionate,2-(2-methoxyethoxy)ethyl 3-(1-pyrrolidinyl)propionate, butyl3-morpholinopropionate, cyclohexyl 3-piperidinopropionate,α-(1-pyrrolidinyl)methyl-γ-butyrolactone, β-piperidino-γ-butyrolactone,β-morpholino-δ-valerolactone, methyl 1-pyrrolidinylacetate, methylpiperidinoacetate, methyl morpholinoacetate, methylthiomorpholinoacetate, ethyl 1-pyrrolidinylacetate, and 2-methoxyethylmorpholinoacetate.

[0381] Also, one or more of cyano-bearing basic compounds having thefollowing general formulae (D3) to (D6) may be blended.

[0382] Herein, X′, R³⁰⁷ and w are as defined above, and R³⁰⁸ and R³⁰⁹are each independently a straight or branched alkylene group of 1 to 4carbon atoms.

[0383] Illustrative examples of the cyano-bearing basic compounds havingformulae (D3) to (D6) include 3-(diethylamino)propiononitrile,N,N-bis(2-hydroxyethyl)-3-aminopropiononitrile,N,N-bis(2-acetoxyethyl)-3-aminopropiononitrile,N,N-bis(2-formyloxyethyl)-3-aminopropiononitrile,N,N-bis(2-methoxyethyl)-3-aminopropiononitrile,N,N-bis[2-(methoxymethoxy)ethyl]-3-aminopropiononitrile, methylN-(2-cyanoethyl)-N-(2-methoxyethyl)-3-aminopropionate, methylN-(2-cyanoethyl)-N-(2-hydroxyethyl)-3-aminopropionate, methylN-(2-acetoxyethyl)-N-(2-cyanoethyl)-3-aminopropionate,N-(2-cyanoethyl)-N-ethyl-3-aminopropiononitrile,N-(2-cyanoethyl)-N-(2-hydroxyethyl)-3-aminopropiononitrile,N-(2-acetoxyethyl)-N-(2-cyanoethyl)-3-aminopropiononitrile,N-(2-cyanoethyl)-N-(2-formyloxyethyl)-3-aminopropiononitrile,N-(2-cyanoethyl)-N-(2-methoxyethyl)-3-aminopropiononitrile,N-(2-cyanoethyl)-N-[2-(methoxymethoxy)ethyl]-3-aminopropiononitrile,N-(2-cyanoethyl)-N-(3-hydroxy-1-propyl)-3-aminopropiononitrile,N-(3-acetoxy-1-propyl)-N-(2-cyanoethyl)-3-aminopropiononitrile,N-(2-cyanoethyl)-N-(3-formyloxy-1-propyl)-3-aminopropiononitrile,N-(2-cyanoethyl)-N-tetrahydrofurfuryl-3-aminopropiononitrile,N,N-bis(2-cyanoethyl)-3-aminopropiononitrile, diethylaminoacetonitrile,N,N-bis(2-hydroxyethyl)aminoacetonitrile,N,N-bis(2-acetoxyethyl)aminoacetonitrile,N,N-bis(2-formyloxyethyl)aminoacetonitrile,N,N-bis(2-methoxyethyl)aminoacetonitrile,N,N-bis[2-(methoxymethoxy)ethyl]aminoacetonitrile, methylN-cyanomethyl-N-(2-methoxyethyl)-3-aminopropionate, methylN-cyanomethyl-N-(2-hydroxyethyl)-3-aminopropionate, methylN-(2-acetoxyethyl)-N-cyanomethyl-3-aminopropionate,N-cyanomethyl-N-(2-hydroxyethyl)aminoacetonitrile,N-(2-acetoxyethyl)-N-(cyanomethyl)aminoacetonitrile,N-cyanomethyl-N-(2-formyloxyethyl)aminoacetonitrile,N-cyanomethyl-N-(2-methoxyethyl)aminoacetonitrile,N-cyanomethyl-N-[2-(methoxymethoxy)ethyl)aminoacetonitrile,N-cyanomethyl-N-(3-hydroxy-1-propyl)aminoacetonitrile,N-(3-acetoxy-1-propyl)-N-(cyanomethyl)aminoacetonitrile,N-cyanomethyl-N-(3-formyloxy-1-propyl)aminoacetonitrile,N,N-bis(cyanomethyl)aminoacetonitrile, 1-pyrrolidinepropiononitrile,1-piperidinepropiononitrile, 4-morpholinepropiononitrile,1-pyrrolidineacetonitrile, 1-piperidineacetonitrile,4-morpholineacetonitrile, cyanomethyl 3-diethylaminopropionate,cyanomethyl N,N-bis(2-hydroxyethyl)-3-aminopropionate, cyanomethylN,N-bis(2-acetoxyethyl)-3-aminopropionate, cyanomethylN,N-bis(2-formyloxyethyl)-3-aminopropionate, cyanomethylN,N-bis(2-methoxyethyl)-3-aminopropionate, cyanomethylN,N-bis[2-(methoxymethoxy)ethyl]-3-aminopropionate, 2-cyanoethyl3-diethylaminopropionate, 2-cyanoethylN,N-bis(2-hydroxyethyl)-3-aminopropionate, 2-cyanoethylN,N-bis(2-acetoxyethyl)-3-aminopropionate, 2-cyanoethylN,N-bis(2-formyloxyethyl)-3-aminopropionate, 2-cyanoethylN,N-bis(2-methoxyethyl)-3-aminopropionate, 2-cyanoethylN,N-bis[2-(methoxymethoxy)ethyl]-3-aminopropionate, cyanomethyl1-pyrrolidinepropionate, cyanomethyl 1-piperidinepropionate, cyanomethyl4-morpholinepropionate, 2-cyanoethyl 1-pyrrolidinepropionate,2-cyanoethyl 1-piperidinepropionate, and 2-cyanoethyl4-morpholinepropionate.

[0384] The basic compounds may be used alone or in admixture of two ormore. The basic compound is preferably formulated in an amount of 0 to 2parts, and especially 0.01 to 1 part by weight, per 100 parts by weightof the solids in the resist composition. The use of more than 2 parts ofthe basis compound would result in too low a sensitivity.

[0385] Component (E)

[0386] Illustrative, non-limiting, examples of the organic acidderivatives (E) include phenol, cresol, catechol, resorcinol,pyrogallol, fluoroglycin, bis(4-hydroxyphenyl)methane,2,2-bis(4′-hydroxyphenyl)propane, bis(4-hydroxyphenyl)sulfone,1,1,1-tris(4′-hydroxyphenyl)ethane, 1,1,2-tris(4′-hydroxyphenyl)ethane,hydroxybenzophenone, 4-hydroxyphenylacetic acid, 3-hydroxyphenylaceticacid, 2-hydroxyphenylacetic acid, 3-(4-hydroxyphenyl)propionic acid,3-(2-hydroxyphenyl)propionic acid, 2,5-dihydroxyphenylacetic acid,3,4-dihydroxyphenylacetic acid, 1,2-phenylenediacetic acid,1,3-phenylenediacetic acid, 1,4-phenylenediacetic acid,1,2-phenylenedioxydiacetic acid, 1,4-phenylenedipropanoic acid, benzoicacid, salicylic acid, 4,4-bis(4′-hydroxyphenyl)valeric acid,4-tert-butoxyphenylacetic acid, 4-(4-hydroxyphenyl)butyric acid,3,4-dihydroxymandelic acid, and 4-hydroxymandelic acid. Of these,salicylic acid and 4,4-bis(4′-hydroxyphenyl)valeric acid are preferred.They may be used alone or in admixture of two or more.

[0387] In the resist composition comprising the sulfonyldiazomethane asthe photoacid generator according to the invention, the organic acidderivative is preferably formulated in an amount of up to 5 parts, andespecially up to 1 part by weight, per 100 parts by weight of the solidsin the resist composition. The use of more than 5 parts of the organicacid derivative would result in too low a resolution. Depending on thecombination of the other components in the resist composition, theorganic acid derivative may be omitted.

[0388] Component (F)

[0389] Component (F) is an organic solvent. Illustrative, non-limiting,examples include butyl acetate, amyl acetate, cyclohexyl acetate,3-methoxybutyl acetate, methyl ethyl ketone, methyl amyl ketone,cyclohexanone, cyclopentanone, 3-ethoxyethyl propionate, 3-ethoxymethylpropionate, 3-methoxymethyl propionate, methyl acetoacetate, ethylacetoacetate, diacetone alcohol, methylpyruvate, ethyl pyruvate,propylene glycol monomethyl ether, propylene glycol monoethyl ether,propylene glycol monomethyl ether propionate, propylene glycol monoethylether propionate, ethylene glycol monomethyl ether, ethylene glycolmonoethyl ether, diethylene glycol monomethyl ether, diethylene glycolmonoethyl ether, 3-methyl-3-methoxybutanol, N-methylpyrrolidone,dimethyl sulfoxide, γ-butyrolactone, propylene glycol methyl etheracetate, propylene glycol ethyl ether acetate, propylene glycol propylether acetate, methyl lactate, ethyl lactate, propyl lactate, andtetramethylsulfonic acid. Of these, the propylene glycol alkyl etheracetates and alkyl lactates are especially preferred. The solvents maybe used alone or in admixture of two or more. An exemplary usefulsolvent mixture is a mixture of a propylene glycol alkyl ether acetateand an alkyl lactate. It is noted that the alkyl groups of the propyleneglycol alkyl ether acetates are preferably those of 1 to 4 carbon atoms,for example, methyl, ethyl and propyl, with methyl and ethyl beingespecially preferred. Since the propylene glycol alkyl ether acetatesinclude 1,2- and 1,3-substituted ones, each includes three isomersdepending on the combination of substituted positions, which may be usedalone or in admixture.

[0390] When the propylene glycol alkyl ether acetate is used as thesolvent, it preferably accounts for at least 50% by weight of the entiresolvent. Also when the alkyl lactate is used as the solvent, itpreferably accounts for at least 50% by weight of the entire solvent.When a mixture of propylene glycol alkyl ether acetate and alkyl lactateis used as the solvent, that mixture preferably accounts for at least50% by weight of the entire solvent. In this solvent mixture, it isfurther preferred that the propylene glycol alkyl ether acetate is 60 to95% by weight and the alkyl lactate is 40 to 5% by weight. A lowerproportion of the propylene glycol alkyl ether acetate would invite aproblem of inefficient coating whereas a higher proportion thereof wouldprovide insufficient dissolution and allow for particle and foreignmatter formation. A lower proportion of the alkyl lactate would provideinsufficient dissolution and cause the problem of many particles andforeign matter whereas a higher proportion thereof would lead to acomposition which has a too high viscosity to apply and loses storagestability.

[0391] The solvent is preferably used in an amount of 300 to 2,000 partsby weight, especially 400 to 1,000 parts by weight per 100 parts byweight of the solids in the resist composition. The solventconcentration is not limited thereto as long as a film can be formed byexisting methods.

[0392] Component (G)

[0393] In one preferred embodiment, the resist composition furthercontains (G) a compound with a molecular weight of up to 3,000 whichchanges its solubility in an alkaline developer under the action of anacid, that is, a dissolution inhibitor. Typically, a compound obtainedby partially or entirely substituting acid labile substituents on aphenol or carboxylic acid derivative having a molecular weight of up to2,500 is added as the dissolution inhibitor.

[0394] Examples of the phenol or carboxylic acid derivative having amolecular weight of up to 2,500 include bisphenol A, bisphenol H,bisphenol S, 4,4-bis(4′-hydroxyphenyl)valeric acid,tris(4-hydroxyphenyl)methane, 1,1,1-tris(4′-hydroxyphenyl)ethane,1,1,2-tris(4′-hydroxyphenyl)ethane, phenolphthalein, andthymolphthalein. The acid labile substituents are the same as thoseexemplified as the acid labile groups in the polymer.

[0395] Illustrative, non-limiting, examples of the dissolutioninhibitors which are useful herein include

[0396] bis(4-(2′-tetrahydropyranyloxy)phenyl)methane,

[0397] bis(4-(2′-tetrahydrofuranyloxy)phenyl)methane,

[0398] bis(4-tert-butoxyphenyl)methane,

[0399] bis(4-tert-butoxycarbonyloxyphenyl)methane,

[0400] bis(4-tert-butoxycarbonylmethyloxyphenyl)methane,

[0401] bis(4-(1′-ethoxyethoxy)phenyl)methane,

[0402] bis(4-(1′-ethoxypropyloxy)phenyl)methane,

[0403] 2,2-bis(4′-(2″-tetrahydropyranyloxy))propane,

[0404] 2,2-bis(4′-(2″-tetrahydrofuranyloxy)phenyl)propane,

[0405] 2,2-bis(4′-tert-butoxyphenyl)propane,

[0406] 2,2-bis(4′-tert-butoxycarbonyloxyphenyl)propane,

[0407] 2,2-bis(4-tert-butoxycarbonylmethyloxyphenyl)propane,

[0408] 2,2-bis(4′-(1″-ethoxyethoxy)phenyl)propane,

[0409] 2,2-bis(4′-(1″-ethoxypropyloxy)phenyl)propane,

[0410] tert-butyl 4,4-bis(4′-(2″-tetrahydropyranyloxy)phenyl)valerate,

[0411] tert-butyl 4,4-bis(4′-(2″-tetrahydrofuranyloxy)phenyl)valerate,

[0412] tert-butyl 4,4-bis(4′-tert-butoxyphenyl)valerate,

[0413] tert-butyl 4,4-bis(4-tert-butoxycarbonyloxyphenyl)valerate,

[0414] tert-butyl4,4-bis(4′-tert-butoxycarbonylmethyloxyphenyl)valerate,

[0415] tert-butyl 4,4-bis(4′-(1″-ethoxyethoxy)phenyl)valerate,

[0416] tert-butyl 4,4-bis(4′-(1″-ethoxypropyloxy)phenyl)valerate,

[0417] tris(4-(2′-tetrahydropyranyloxy)phenyl)methane,

[0418] tris(4-(2′-tetrahydrofuranyloxy)phenyl)methane,

[0419] tris(4-tert-butoxyphenyl)methane,

[0420] tris(4-tert-butoxycarbonyloxyphenyl)methane,

[0421] tris(4-tert-butoxycarbonyloxymethylphenyl)methane,

[0422] tris(4-(1′-ethoxyethoxy)phenyl)methane,

[0423] tris(4-(1′-ethoxypropyloxy)phenyl)methane,

[0424] 1,1,2-tris(4′-(2″-tetrahydropyranyloxy)phenyl)ethane,

[0425] 1,1,2-tris(4′-(2″-tetrahydrofuranyloxy)phenyl)ethane,

[0426] 1,1,2-tris(4′-tert-butoxyphenyl)ethane,

[0427] 1,1,2-tris(4′-tert-butoxycarbonyloxyphenyl)ethane,

[0428] 1,1,2-tris(4′-tert-butoxycarbonylmethyloxyphenyl)ethane,

[0429] 1,1,2-tris(4′-(1′-ethoxyethoxy)phenyl)ethane, and

[0430] 1,1,2-tris(4′-(1′-ethoxypropyloxy)phenyl)ethane.

[0431] In the resist composition comprising the sulfonyldiazomethane offormula (1) or (1a) as the photoacid generator according to theinvention, an appropriate amount of the dissolution inhibitor is up to20 parts, and especially up to 15 parts by weight per 100 parts byweight of the solids in the resist composition. With more than 20 partsof the dissolution inhibitor, the resist composition becomes less heatresistant because of an increased content of monomer components.

[0432] Component (H)

[0433] In a chemical amplification, negative working, resist compositionas well, the sulfonyldiazomethane of formula (1) or (1a) according tothe invention may be used as the photoacid generator. This compositionfurther contains an alkali-soluble resin as component (H), examples ofwhich are intermediates of the above-described component (A) though notlimited thereto. Examples of the alkali-soluble resin includepoly(p-hydroxystyrene), poly(m-hydroxystyrene),poly(4-hydroxy-2-methylstyrene), poly(4-hydroxy-3-methylstyrene),poly(α-methyl-p-hydroxystyrene),

[0434] partially hydrogenated p-hydroxystyrene copolymers,p-hydroxystyrene-α-methyl-p-hydroxystyrene copolymers,p-hydroxystyrene-α-methylstyrene copolymers, p-hydroxystyrene-styrenecopolymers, p-hydroxystyrene-m-hydroxystyrene copolymers,p-hydroxystyrene-styrene copolymers, p-hydroxystyrene-acrylic acidcopolymers, p-hydroxystyrene-methacrylic acid copolymers,p-hydroxystyrene-methyl methacrylate copolymers,p-hydroxystyrene-acrylic acid-methyl methacrylate copolymers,p-hydroxystyrene-methyl acrylate copolymers,p-hydroxystyrene-methacrylic acid-methyl methacrylate copolymers,poly(methacrylic acid), poly(acrylic acid), acrylic acid-methyl acrylatecopolymers, methacrylic acid-methyl methacrylate copolymers, acrylicacid-maleimide copolymers, methacrylic acid-maleimide copolymers,p-hydroxystyrene-acrylic acid-maleimide copolymers, andp-hydroxystyrene-methacrylic acid-maleimide copolymers, but are notlimited to these combinations.

[0435] Preferred are poly(p-hydroxystyrene), partially hydrogenatedp-hydroxystyrene copolymers, p-hydroxystyrene-styrene copolymers,p-hydroxystyrene-acrylic acid copolymers, andp-hydroxystyrene-methacrylic acid copolymers.

[0436] Alkali-soluble resins comprising units of the following formula(2), (2′), (2″) or (2″′) are especially preferred.

[0437] Herein R⁴ is hydrogen or methyl; and R⁵ is a straight, branchedor cyclic alkyl group of 1 to 8 carbon atoms. The subscript x is 0 or apositive integer; y is a positive integer, satisfying x+y≦5, yy is 0 ora positive integer, satisfying x+yy≦5; M and N are positive integers,satisfying 0<N/(M+N)≦0.5; A and B are positive integers, C is 0 or apositive integer, satisfying 0<B/(A+B+C)≦0.5, ZZ is a divalent groupselected from among CH₂, CH(OH), CR⁵(OH), C═O and C(OR⁵)(OH), or atrivalent organic group represented by —C(OH)═; F is independently apositive integer, and H is a positive integer, satisfying0.001≦H/(H+F)≦0.1; and XX is 1 or 2.

[0438] The polymer should preferably have a weight average molecularweight (Mw) of 3,000 to 100,000. Many polymers with Mw of less than3,000 do not perform well and are poor in heat resistance and filmformation. Many polymers with Mw of more than 100,000 give rise to aproblem with respect to dissolution in the resist solvent and developer.The polymer should also preferably have a dispersity (Mw/Mn) of up to3.5, and more preferably up to 1.5. With a dispersity of more than 3.5,resolution is low in many cases. Although the preparation method is notcritical, a poly(p-hydroxystyrene) or similar polymer with a lowdispersity or narrow dispersion can be synthesized by living anionpolymerization.

[0439] To impart a certain function, suitable substituent groups may beintroduced into some of the phenolic hydroxyl and carboxyl groups on theforegoing polymer. Exemplary and preferred are substituent groups forimproving adhesion to the substrate, substituent groups for improvingetching resistance, and especially substituent groups which arerelatively stable against acid and alkali and effective for controllingsuch that the dissolution rate in an alkali developer of unexposed andlow exposed areas of a resist film may not become too high.Illustrative, non-limiting, substituent groups include 2-hydroxyethyl,2-hydroxypropyl, methoxymethyl, methoxycarbonyl, ethoxycarbonyl,methoxycarbonylmethyl, ethoxycarbonylmethyl, 4-methyl-2-oxo-4-oxolanyl,4-methyl-2-oxo-4-oxanyl, methyl, ethyl, n-propyl, isopropyl, n-butyl,sec-butyl, acetyl, pivaloyl, adamantyl, isobornyl, and cyclohexyl. It isalso possible to introduce acid-decomposable substituent groups such ast-butoxycarbonyl and relatively acid-undecomposable substituent groupssuch as t-butyl and t-butoxycarbonylmethyl.

[0440] In the resist composition, the above resin is blended in anydesired amount, preferably of 65 to 99 parts by weight, especially 70 to98 parts by weight per 100 parts by weight of the solids.

[0441] Also contained in the negative resist composition is (I) an acidcrosslinking agent capable of forming a crosslinked structure under theaction of an acid. Typical acid crosslinking agents are compounds havingat least two hydroxymethyl, alkoxymethyl, epoxy or vinyl ether groups ina molecule. Substituted glycoluril derivatives, urea derivatives, andhexa(methoxymethyl)melamine compounds are suitable as the acidcrosslinking agent in the chemically amplified, negative resistcomposition comprising the sulfonyldiazomethane. Examples includeN,N,N′,N′-tetramethoxymethylurea, hexamethoxymethylmelamine,tetraalkoxymethyl-substituted glycoluril compounds such astetrahydroxymethyl-substituted glycoluril andtetramethoxymethylglycoluril, and condensates of phenolic compounds suchas substituted or unsubstituted bis(hydroxymethylphenol) compounds andbisphenol A with epichlorohydrin. Especially preferred acid crosslinkingagents are 1,3,5,7-tetraalkoxymethylglycolurils such as1,3,5,7-tetramethoxymethylglycoluril,1,3,5,7-tetrahydroxymethylglycoluril, 2,6-dihydroxymethyl-p-cresol,2,6-dihydroxymethylphenol, 2,2′,6,6′-tetrahydroxymethyl-bisphenol A,1,4-bis[2-(2-hydroxypropyl)]benzene, N,N,N′,N′-tetramethoxymethylurea,and hexamethoxymethylmelamine.

[0442] An appropriate amount of the acid crosslinking agent is, but notlimited thereto, about 1 to 20 parts, and especially about 5 to 15 partsby weight per 100 parts by weight of the solids in the resistcomposition. The acid crosslinking agents may be used alone or inadmixture of any.

[0443] Component (J) is an alkali-soluble compound having a molecularweight of up to 2,500. Any suitable compound may be used although acompound having at least two phenol and/or carboxyl groups is preferred.Illustrative, non-limiting, examples of the alkali-soluble compound (J)include cresol, catechol, resorcinol, pyrogallol, fluoroglycin,bis(4-hydroxyphenyl)methane, 2,2-bis(4′-hydroxyphenyl)propane,bis(4-hydroxyphenyl)sulfone, 1,1,1-tris(4′-hydroxyphenyl)ethane,1,1,2-tris(4′-hydroxyphenyl)ethane, hydroxybenzophenone,4-hydroxyphenylacetic acid, 3-hydroxyphenylacetic acid,2-hydroxyphenylacetic acid, 3-(4-hydroxyphenyl)propionic acid,3-(2-hydroxyphenyl)propionic acid, 2,5-dihydroxyphenylacetic acid,3,4-dihydroxyphenylacetic acid, 1,2-phenylenediacetic acid,1,3-phenylenediacetic acid, 1,4-phenylenediacetic acid,1,2-phenylenedioxydiacetic acid, 1,4-phenylenedipropanoic acid, benzoicacid, salicylic acid, 4,4-bis(4′-hydroxyphenyl)valeric acid,4-tert-butoxyphenylacetic acid, 4-(4-hydroxyphenyl)butyric acid,3,4-dihydroxymandelic acid, and 4-hydroxymandelic acid. Of these,salicylic acid and 4,4-bis(4′-hydroxyphenyl)valeric acid are preferred.They may be used alone or in admixture of two or more. Thealkali-soluble compound is blended in any desired amount, preferably of0 to 20 parts by weight, especially 2 to 10 parts by weight per 100parts by weight of the solids in the resist composition.

[0444] In the chemical amplification type resist composition accordingto the invention, there may be added such additives as a surfactant forimproving coating, and a light absorbing agent for reducing diffusereflection from the substrate.

[0445] Illustrative, non-limiting, examples of the surfactant includenonionic surfactants, for example, polyoxyethylene alkyl ethers such aspolyoxyethylene lauryl ether, polyoxyethylene stearyl ether,polyoxyethylene cetyl ether, and polyoxyethylene oleyl ether,polyoxyethylene alkylaryl ethers such as polyoxyethylene octylphenolether and polyoxyethylene nonylphenol ether, polyoxyethylenepolyoxypropylene block copolymers, sorbitan fatty acid esters such assorbitan monolaurate, sorbitan monopalmitate, and sorbitan monostearate,and polyoxyethylene sorbitan fatty acid esters such as polyoxyethylenesorbitan monolaurate, polyoxyethylene sorbitan monopalmitate,polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitantrioleate, and polyoxyethylene sorbitan tristearate; fluorochemicalsurfactants such as EFTOP EF301, EF303 and EF352 (Tohkem Products Co.,Ltd.), Megaface F171, F172 and F173 (Dainippon Ink & Chemicals, Inc.),Fluorad FC430 and FC431 (Sumitomo 3M Co., Ltd.), Aashiguard AG710,Surflon S-381, S-382, SC101, SC102, SC103, SC104, SC105, SC106, SurfynolE1004, KH-10, KH-20, KH-30 and KH-40 (Asahi Glass Co., Ltd.);organosiloxane polymers KP341, X-70-092 and X-70-093 (Shin-Etsu ChemicalCo., Ltd.), acrylic acid or methacrylic acid Polyflow No. 75 and No. 95(Kyoeisha Ushi Kagaku Kogyo K.K.). Inter alia, FC430, Surflon S-381,Surfynol E1004, KH-20 and KH-30 are preferred. These surfactants may beused alone or in admixture.

[0446] In the chemical amplification type resist composition accordingto the invention, the surfactant is preferably formulated in an amountof up to 2 parts, and especially up to 1 part by weight, per 100 partsby weight of the solids in the resist composition.

[0447] In the chemical amplification type resist composition accordingto the invention, a UV absorber may be added. Those UV absorbersdescribed in JP-A 11-190904 are useful, but the invention is not limitedthereto. Exemplary UV absorbers are diaryl sulfoxide derivatives such asbis(4-hydroxyphenyl)sulfoxide, bis(4-tert-butoxyphenyl)sulfoxide,bis(4-tert-butoxycarbonyloxyphenyl)sulfoxide, andbis[4-(1-ethoxyethoxy)phenyl]sulfoxide; diarylsulfone derivatives suchas bis(4-hydroxyphenyl)sulfone, bis(4-tert-butoxyphenyl)sulfone,bis(4-tert-butoxycarbonyloxyphenyl)sulfone,bis[4-(1-ethoxyethoxy)phenyl]sulfone, andbis[4-(1-ethoxypropoxy)phenyl]sulfone; diazo compounds such asbenzoquinonediazide, naphthoquinonediazide, anthraquinonediazide,diazofluorene, diazotetralone, and diazophenanthrone; quinonediazidegroup-containing compounds such as complete or partial ester compoundsbetween naphthoquinone-1,2-diazide-5-sulfonic acid chloride and2,3,4-trihydroxybenzophenone and complete or partial ester compoundsbetween naphthoquinone-1,2-diazide-4-sulfonic acid chloride and2,4,4′-trihydroxybenzophenone; tert-butyl 9-anthracenecarboxylate,tert-amyl 9-anthracenecarboxylate, tert-methoxymethyl9-anthracenecarboxylate, tert-ethoxyethyl 9-anthracenecarboxylate,2-tert-tetrahydropyranyl 9-anthracenecarboxylate, and2-tert-tetrahydrofuranyl 9-anthracenecarboxylate. The UV absorber may ormay not be added to the resist composition depending on the type ofresist composition. An appropriate amount of UV absorber, if added, is 0to 10 parts, more preferably 0.5 to 10 parts, most preferably 1 to 5parts by weight per 100 parts by weight of the base resin.

[0448] For the microfabrication of integrated circuits, any well-knownlithography may be used to form a resist pattern from the chemicalamplification type resist composition comprising thesulfonyldiazomethane photoacid generator of formula (1) or (1a) and theresin which changes solubility in an alkaline developer under the actionof acid according to the invention.

[0449] The composition is applied onto a substrate (e.g., Si, SiO₂, SiN,SiON, TiN, WSi, BPSG, SOG, organic anti-reflecting film, etc.) by asuitable coating technique such as spin coating, roll coating, flowcoating, dip coating, spray coating or doctor coating. The coating isprebaked on a hot plate at a temperature of 60 to 150° C. for about 1 to10 minutes, preferably 80 to 120° C. for 1 to 5 minutes. The resultingresist film is generally 0.1 to 2.0 μm thick. With a mask having adesired pattern placed above the resist film, the resist film is thenexposed to actinic radiation, preferably having an exposure wavelengthof up to 300 nm, such as UV, deep-UV, electron beams, x-rays, excimerlaser light, γ-rays and synchrotron radiation in an exposure dose ofabout 1 to 200 mJ/cm², preferably about 10 to 100 mJ/cm². The film isfurther baked on a hot plate at 60 to 150° C. for 1 to 5 minutes,preferably 80 to 120° C. for 1 to 3 minutes (post-exposure baking=PEB).

[0450] Thereafter the resist film is developed with a developer in theform of an aqueous base solution, for example, 0.1 to 5%, preferably 2to 3% aqueous solution of tetramethylammonium hydroxide (TMAH) for 0.1to 3 minutes, preferably 0.5 to 2 minutes by conventional techniquessuch as dipping, puddling or spraying. In this way, a desired resistpattern is formed on the substrate. It is appreciated that the resistcomposition of the invention is best suited for micro-patterning usingsuch actinic radiation as deep UV with a wavelength of 254 to 193 nm,vacuum UV with a wavelength of 157 nm, electron beams, x-rays, excimerlaser light, γ-rays and synchrotron radiation. With any of theabove-described parameters outside the above-described range, theprocess may sometimes fail to produce the desired pattern.

EXAMPLE

[0451] Examples of the invention are given below by way of illustrationand not by way of limitation.

Synthesis Example 1

[0452] Synthesis of 2-(n-hexyloxy)-5-tert-butylthiophenol

[0453] In 158 g of ethanol were dissolved 105 g (0.7 mol) of4-tert-butylphenol and 30.8 g (0.77 mol) of sodium hydroxide. To thesolution at 70° C., 127 g (0.77 mol) of n-bromohexane was addeddropwise. The solution was allowed to ripen for 4 hours and cooled toroom temperature, after which 158 g of water was added. The oily phasewas separated therefrom and concentrated on a rotary evaporator,yielding 167 g of an oily matter. Then 167 g of the oily matter wasdissolved in 600 g of dichloromethane. While cooling in an ice/waterbath, 100 g (0.625 mol) of bromine was added dropwise at a temperaturebelow 10° C. After the completion of dropwise addition, 300 g of waterwas added. The organic layer was separated and washed with a saturatedsodium hydrogen carbonate aqueous solution. The organic layer wasconcentrated on a rotary evaporator, yielding 208 g of an oily matter.On analysis by gas chromatography/mass analysis and gas chromatography,the oily matter was found to contain 90% of2-bromo-4-tert-butyl-1-n-hexyloxybenzene.

[0454] Using 208 g (0.60 mol) of the2-bromo-4-tert-butyl-1-n-hexyloxybenzene (90% pure), 15.4 g (0.63 mol)of metallic magnesium and 450 g of tetrahydrofuran, a Grignard reagentwas prepared in a conventional manner. The Grignard reagent was icecooled, to which 18.3 g (0.57 mol) of colloidal sulfur was added at atemperature below 20° C. The solution was allowed to ripen for 2 hoursat room temperature, then ice cooled again. To the solution, 90 g ofconc. hydrochloric acid (12N) and 300 g of water were added. The organiclayer was separated and concentrated on a rotary evaporator, yielding180 g of an oily matter. This concentrate was distilled in vacuum(boiling point 132-135° C./0.5 Torr), obtaining 115 g of the endcompound, 2-(n-hexyloxy)-5-tert-butylthiophenol with a purity of 90%(yield 64%).

Synthesis Example 2

[0455] Synthesis ofbis(2-(n-hexyloxy)-5-tert-butylbenzenesulfonyl)methane

[0456] In 230 g of ethanol were dissolved 115 g (0.39 mol) of the above2-(n-hexyloxy)-5-tert-butylthiophenol and 16.4 g (0.41 mol) of sodiumhydroxide. Then 23.1 g (0.27 mol) of dichloromethane was added dropwiseat a temperature below 50° C. The solution was heated on an oil bath to60° C. and allowed to ripen at the temperature for 3 hours. The solutionwas allowed to cool down to room temperature, after which 420 g of waterand 300 g of dichloromethane were added. The organic layer was separatedand the solvent was removed by means of a rotary evaporator, yielding124 g of formaldehyde bis(2-(n-hexyloxy)-5-tert-butylbenzenethio)acetal.

[0457] To 400 g of acetonitrile were added 124 g of the formaldehydebis(2-(n-hexyloxy)-5-tert-butylbenzenethio)acetal and 1.9 g (0.0058 mol)of sodium tungstate. The solution was heated on an oil bath to 70° C.Then 94 g (0.97 mol) of 35% aqueous hydrogen peroxide was added dropwiseat a temperature below 75° C. The solution was held at the temperaturefor 4 hours and then cooled on an ice bath whereupon white crystalsprecipitated. The crystals were filtered, collecting 95 g (yield 80%) ofthe end bis(2-(n-hexyloxy)-5-tert-butylbenzenesulfonyl)methane.

Synthesis Example 3

[0458] Synthesis ofbis(2-(n-hexyloxy)-5-tert-butylbenzenesulfonyl)diazomethane

[0459] In 120 g of dichloromethane were dissolved 12.1 g (0.02 mol) ofthe above bis(2-(n-hexyloxy)-5-tert-butylbenzenesulfonyl)methane and 5.9g (0.03 mol) of p-toluenesulfonylazide. The solution was cooled on anice bath, and 3.0 g (0.02 mol) of 1,8-diazabicyclo[5.4.0]-7-undecene(DBU) was added at a temperature below 5° C. The solution was allowed toripen at room temperature for 2 hour, after which 100 g of water wasadded. The organic layer was separated and washed with 100 g of water,after which the solvent was removed by means of a rotary evaporator,obtaining 35 g of an oily matter. It was purified by silica gel columnchromatography (eluent: dichloromethane), obtaining 4.5 g (yield 35%) ofthe end compound,bis(2-(n-hexyloxy)-5-tert-butylbenzenesulfonyl)diazomethane.

[0460] The thus obtainedbis(2-(n-hexyloxy)-5-tert-butylbenzenesulfonyl)diazomethane was analyzedby nuclear magnetic resonance (NMR) spectroscopy, infrared (IR)absorption spectroscopy and thermogravimetric analysis (Tdec), with theresults shown below.

¹H-NMR: CDCl₃ (ppm) (1) Ha 0.887-0.934 triplet  6H (2) Hb, Hc 1.30-1.40multiplet  8H (3) Hi 1.296 singlet 18H (4) Hd 1.430-1.527 multiplet  4H(5) He 1.812-1.908 multiplet  4H (6) Hf 4.051-4.096 triplet  4H (7) Hg6.878-6.907 doublet  2H (8) Hh 7.510-7.547 quadruplet  2H (9) Hj7.800-7.808 doublet  2H

[0461] IR (cm⁻¹): 2960, 2873, 2859, 2121, 1497, 1466, 1365, 1350, 1336,1294, 1269, 1169, 1149, 1066, 982, 829, 673, 594, 580, 552

[0462] Thermogravimetric analysis: 146.6° C. (the temperature at which aweight change of −0.1 wt % occurred upon heating at a rate of 10° C./minfrom room temperature)

Synthesis Example 4

[0463] Synthesis of 2-(n-hexyloxy)-5-methylthiophenol

[0464] In 92 g of ethanol were dissolved 46.7 g (0.25 mol) of2-bromo-4-methylphenol and 11.0 g (0.275 mol) of sodium hydroxide. Tothe solution at 70° C., 45.4 g (0.275 mol) of n-bromohexane was addeddropwise. The solution was allowed to ripen for 4 hours and cooled toroom temperature, after which 190 g of water was added. The oily phasewas separated therefrom and concentrated on a rotary evaporator,yielding 67 g of an oily matter. On analysis by gas chromatography/massanalysis and gas chromatography, the oily matter was found to contain95% of 2-bromo-4-tert-butyl-1-n-hexyloxybenzene.

[0465] Using 67 g (0.235 mol) of the2-bromo-4-tert-butyl-1-n-hexyloxybenzene (95% pure), 6.1 g (0.25 mol) ofmetallic magnesium and 163 g of tetrahydrofuran, a Grignard reagent wasprepared in a conventional manner. The Grignard reagent was ice cooled,to which 7.45 g (0.23 mol) of colloidal sulfur was added at atemperature below 20° C. The solution was allowed to ripen for 2 hoursat room temperature, then ice cooled again. To the solution, 38 g ofconc. hydrochloric acid (12N) and 125 g of water were added. The organiclayer was separated and concentrated on a rotary evaporator, yielding 54g of an oily matter. This concentrate was distilled in vacuum (boilingpoint 120-128° C./0.5 Torr), obtaining 39 g of the end compound,2-(n-hexyloxy)-5-methylthiophenol with a purity of 97% (yield 70%).

Synthesis Example 5

[0466] Synthesis of bis(2-(n-hexyloxy)-5-methylbenzenesulfonyl)methane

[0467] In 80 g of ethanol were dissolved 39 g (0.167 mol) of the above2-(n-hexyloxy)-5-methylthiophenol and 7.0 g (0.175 mol) of sodiumhydroxide. Then 9.9 g (0.117 mol) of dichloromethane was added dropwiseat a temperature below 50° C. The solution was heated on an oil bath to60° C. and allowed to ripen at the temperature for 3 hours. The solutionwas allowed to cool down to room temperature, after which 160 g of waterand 200 g of dichloromethane were added. The organic layer was separatedand the solvent was removed by means of a rotary evaporator, yielding 42g of formaldehyde bis(2-(n-hexyloxy)-5-methylbenzenethio)acetal.

[0468] To 156 g of acetonitrile were added 42 g of the formaldehydebis(2-(n-hexyloxy)-5-methylbenzenethio)acetal and 0.8 g (0.0025 mol) ofsodium tungstate. The solution was heated on an oil bath to 70° C. Then40.5 g (0.417 mol) of 35% aqueous hydrogen peroxide was added dropwiseat a temperature below 75° C. The solution was held at the temperaturefor 4 hours and then cooled on an ice bath whereupon white crystalsprecipitated. The crystals were filtered, collecting 40 g (yield 91%) ofthe end bis(2-(n-hexyloxy)-5-methylbenzenesulfonyl)methane.

Synthesis Example 6

[0469] Synthesis ofbis(2-(n-hexyloxy)-5-methylbenzenesulfonyl)diazomethane

[0470] In 100 g of dichloromethane were dissolved 10.0 g (0.019 mol) ofthe above bis(2-(n-hexyloxy)-5-methylbenzenesulfonyl)methane and 5.6 g(0.0285 mol) of p-toluenesulfonylazide. The solution was cooled on anice bath, and 2.89 g (0.019 mol) of 1,8-diazabicyclo[5.4.0]-7-undecene(DBU) was added at a temperature below 5° C. The solution was allowed toripen at room temperature for 2 hour, after which 100 g of water wasadded. The organic layer was separated and washed with 100 g of water,after which the solvent was removed by means of a rotary evaporator,obtaining 20 g of an oily matter. It was purified by silica gel columnchromatography (eluent: dichloromethane), obtaining 7.4 g (yield 71%) ofthe end compound,bis(2-(n-hexyloxy)-5-methylbenzenesulfonyl)diazomethane. It was analyzedby NMR, IR and thermogravimetric analysis, with the results shown below.

¹H-NMR: CDCl₃ (ppm) (1) Ha 0.883-0.930 triplet 6H (2) Hb, Hc 1.274-1.40 multiplet 8H (3) Hd  1.40-1.512 multiplet 4H (4) He 1.797-1.893multiplet 4H (5) Hi 2.275 singlet 6H (6) Hf 3.992-4.037 triplet 4H (7)Hg 6.761-6.790 doublet 2H (8) Hh 7.242-7.279 quadruplet 2H (9) Hj7.540-7.549 quadruplet 2H

[0471] IR (cm⁻¹): 2954, 2931, 2129, 1610, 1570, 1498, 1464, 1392, 1344,1331, 1286, 1255, 1232, 1143, 1065, 993, 889, 823, 723, 694, 646, 598,588, 569, 540

[0472] Thermogravimetric analysis: 148° C. (the temperature at which aweight change of −0.1 wt % occurred upon heating at a rate of 10° C./minfrom room temperature)

Synthesis Example 7

[0473] 20 Synthesis ofbis(2-(n-hexyloxy)-5-ethylbenzenesulfonyl)diazomethane

[0474] The end compound,bis(2-(n-hexyloxy)-5-ethylbenzenesulfonyl)diazomethane was synthesizedas in Synthesis Examples 1 to 3 except that 4-ethylphenol was usedinstead of 4-tert-butylphenol in Synthesis Example 1. The results ofNMR, IR and thermogravimetric analyses are shown below.

¹H-NMR: CDCl₃ (ppm)  (1) Ha 0.883-0.930 triplet 6H  (2) Hk 1.165-1.215triplet 6H  (3) Hb, Hc 1.292-1.40  multiplet 8H  (4) Hd  1.40-1.515multiplet 4H  (5) He 1.801-1.896 multiplet 4H  (6) Hi 2.540-2.616quadruplet 4H  (7) Hf 4.003-4.048 triplet 4H  (8) Hg 6.798-6.826 doublet2H  (9) Hh 7.274-7.309 quadruplet 2H (10) Hj 7.567-7.575 doublet 2H

[0475] IR (cm⁻¹): 2951, 2869, 2129, 1608, 1498, 1461, 1344, 1330, 1228,1255, 1230, 1141, 1062, 993, 937, 835, 692, 646, 588, 555, 522

[0476] Thermogravimetric analysis: 141° C. (the temperature at which aweight change of −0.1 wt % occurred upon heating at a rate of 10° C./minfrom room temperature)

Synthesis Example 8

[0477] Synthesis ofbis(2-(n-hexyloxy)-5-isopropylbenzenesulfonyl)diazomethane

[0478] The end compound,bis(2-(n-hexyloxy)-5-isopropylbenzenesulfonyl)diazomethane wassynthesized as in Synthesis Examples 1 to 3 except that4-isopropylphenol was used instead of 4-tert-butylphenol in SynthesisExample 1. The results of NMR, IR and thermogravimetric analyses areshown below.

¹H-NMR: CDCl₃ (ppm)  (1) Ha 0.885-0.931 triplet  6H  (2) Hk 1.203-1.226doublet 12H  (3) Hb, Hc 1.30-1.40 multiplet  8H  (4) Hd  1.40-1.518multiplet  4H  (5) He 1.804-1.900 multiplet  4H  (6) Hi 2.798-2.937multiplet  2H  (7) Hf 4.022-4.068 triplet  4H  (8) Hg 6.840-6.868doublet  2H  (9) Hh 7.331-7.368 quadruplet  2H (10) Hj 7.617-7.625doublet  2H

[0479] IR (cm⁻¹): 2958, 2931, 2871, 2127, 1606, 1494, 1465, 1344, 1330,1290, 1255, 1162, 1143, 1062, 991, 833, 727, 680, 651, 586, 553

[0480] Thermogravimetric analysis: 143° C. (the temperature at which aweight change of −0.1 wt % occurred upon heating at a rate of 10° C./minfrom room temperature)

Synthesis Example 9

[0481] Synthesis ofbis(2-(n-hexyloxy)-5-(2-methoxyethyl)benzenesulfonyl)diazomethane

[0482] The end compound,bis(2-(n-hexyloxy)-5-(2-methoxyethyl)benzenesulfonyl)diazomethane wassynthesized as in Synthesis Examples 1 to 3 except that4-(2-methoxyethyl)phenol was used instead of 4-tert-butylphenol inSynthesis Example 1. The results of NMR, IR and thermogravimetricanalyses are shown below.

¹H-NMR: CDCl₃ (ppm)  (1) Ha 0.880-0.926 triplet 6H  (2) Hb, Hc 1.28-1.40multiplet 8H  (3) Hd  1.40-1.513 multiplet 4H  (4) He 1.801-1.896multiplet 4H  (5) Hi 2.791-2.837 triplet 4H  (6) Hl 3.329 singlet 6H (7) Hk 3.515-3.561 triplet 4H  (8) Hf 4.026-4.071 triplet 4H  (9) Hg6.831-6.859 doublet 2H (10) Hh 7.344-7.380 quadruplet 2H (11) Hj7.611-7.618 doublet 2H

[0483] IR (cm⁻¹): 2959, 2929, 2869, 2130, 1498, 1473, 1349, 1332, 1286,1257, 1143, 1116, 1064, 987, 592, 580, 551

[0484] Thermogravimetric analysis: 144° C. (the temperature at which aweight change of −0.1 wt % occurred upon heating at a rate of 10° C./minfrom room temperature)

Reference Synthesis Example 1

[0485] Synthesis of bis(4-methoxyphenylsulfonyl)diazomethane

[0486] As in Synthesis Examples 1 to 3, the end compound was synthesizedfrom 4-methoxythiphenol (Tokyo Kasei Kogyo Co., Ltd.). The result ofthermogravimetric analysis is shown below.

[0487] Thermogravimetric analysis: 128° C. (the temperature at which aweight change of −0.1 wt % occurred upon heating at a rate of 10° C./minfrom room temperature)

Reference Synthesis Example 2

[0488] Synthesis of bis(4-methylphenylsulfonyl)diazomethane

[0489] As in Synthesis Examples 1 to 3, the end compound was synthesizedfrom 4-methylthiphenol (Tokyo Kasei Kogyo Co., Ltd.). The result ofthermogravimetric analysis is shown below.

[0490] Thermogravimetric analysis: 124° C. (the temperature at which aweight change of −0.1 wt % occurred upon heating at a rate of 10° C./minfrom room temperature)

Examples 1-24 and Comparative Examples 1-3

[0491] Resist materials were formulated in accordance with theformulation shown in Tables 1 to 3. The components used are shown below.

[0492] Polymer A: poly(p-hydroxystyrene) in which hydroxyl groups areprotected with 15 mol % of 1-ethoxyethyl groups and 15 mol % oftert-butoxycarbonyl groups, having a weight average molecular weight of12,000.

[0493] Polymer B: poly(p-hydroxystyrene) in which hydroxyl groups areprotected with 30 mol % of 1-ethoxyethyl groups, having a weight averagemolecular weight of 12,000.

[0494] Polymer C: poly(p-hydroxystyrene) in which hydroxyl groups areprotected with 25 mol % of 1-ethoxyethyl groups and crosslinked with 3mol % of 1,2-propanediol divinyl ether, having a weight averagemolecular weight of 13,000.

[0495] Polymer D: poly(p-hydroxystyrene) in which hydroxyl groups areprotected with 28 mol % of tert-pentyl groups, having a weight averagemolecular weight of 8,000.

[0496] Polymer E: p-hydroxystyrene/2-ethyl-2-adamantyl acrylatecopolymer having a compositional ratio (molar ratio) of 70:30 and aweight average molecular weight of 15,000.

[0497] Polymer F: p-hydroxystyrene/1-ethyl-1-norbornene methacrylatecopolymer having a compositional ratio (molar ratio) of 70:30 and aweight average molecular weight of 15,000.

[0498] Polymer G: p-hydroxystyrene/tert-butyl acrylate copolymer havinga compositional ratio (molar ratio) of 65:35 and a weight averagemolecular weight of 15,000.

[0499] Polymer H: p-hydroxystyrene/1-ethylcyclopentyl methacrylatecopolymer having a compositional ratio (molar ratio) of 65:35 and aweight average molecular weight of 15,000.

[0500] Polymer I: p-hydroxystyrene/1-ethylcyclopentylmethacrylate/p-tert-pentyloxystyrene copolymer having a compositionalratio (molar ratio) of 70:8:22 and a weight average molecular weight of16,000.

[0501] Polymer J: p-hydroxystyrene/1-ethylcyclopentylmethacrylate/styrene copolymer having a compositional ratio (molarratio) of 65:10:25 and a weight average molecular weight of 12,000.

[0502] Polymer K: p-hydroxystyrene/indene copolymer having acompositional ratio (molar ratio) of 80:20 in which hydroxyl groups onthe hydroxystyrene are protected with 20 mol % of tert-butoxycarbonylgroups, and having a weight average molecular weight of 10,000.

[0503] Polymer L: p-hydroxystyrene/indene/2-ethyl-2-adamantylmethacrylate copolymer having a compositional ratio (molar ratio) of82:4:14 and a weight average molecular weight of 8,000.

[0504] Polymer M: p-hydroxystyrene/indene/1-ethyl-1-norbornenemethacrylate copolymer having a compositional ratio (molar ratio) of84:4:12 and a weight average molecular weight of 8,000.

[0505] Polymer N: poly(p-hydroxystyrene) in which hydroxyl groups areprotected with 8 mol % of acetyl groups, having a weight averagemolecular weight of 8,000.

[0506] PAG1: compound of Synthesis Example 3

[0507] PAG2: compound of Synthesis Example 6

[0508] PAG3: compound of Synthesis Example 7

[0509] PAG4: compound of Synthesis Example 8

[0510] PAG5: (4-tert-butoxyphenyl)diphenylsulfonium 10-camphorsulfonate

[0511] PAG6: bis(4-methoxyphenylsulfonyl)diazomethane

[0512] PAG7: bis(cyclohexylsulfonyl)diazomethane

[0513] PAG8: bis(4-methylphenylsulfonyl)diazomethane

[0514] PAG9: N-10-camphorsulfonyloxysuccinimide

[0515] Crosslinker A: 1,3,5,7-tetramethoxymethylglycoluril

[0516] Dissolution inhibitor:bis(4-(2′-tetrahydropyranyloxy)phenyl)methane

[0517] Basic compound A: tri(n-butyl)amine

[0518] Basic compound B: tris(2-methoxyethyl)amine

[0519] Organic acid derivative A: 4,4-bis(4′-hydroxyphenyl)valeric acid

[0520] Organic acid derivative B: salicylic acid

[0521] Surfactant A: FC-430 (Sumitomo 3M Co., Ltd.)

[0522] Surfactant B: Surflon S-381 (Asahi Glass Co., Ltd.)

[0523] UV absorber: 9,10-dimethylanthracene

[0524] Solvent A: propylene glycol methyl ether acetate

[0525] Solvent B: ethyl lactate

[0526] The resist materials thus obtained were each filtered through a0.2-μm Teflon® filter, thereby giving resist solutions. These resistsolutions were spin-coated onto silicon wafers having an organicantireflection film (DUV-44, Brewer Science) of 800 Å thick coatedthereon, so as to give a dry thickness of 0.6 μm.

[0527] The coated wafer was then baked on a hot plate at 100° C. for 90seconds. The resist films were exposed to 2/3 annular illumination usingan excimer laser stepper NSR—S202A (Nikon Corporation, NA=0.6), thenbaked (PEB) at 110° C. for 90 seconds, and developed with a solution of2.38% tetramethylammonium hydroxide in water, thereby giving positivepatterns (Examples 1 to 23 and Comparative Examples 1-3) or negativepattern (Example 24).

[0528] The resulting resist patterns were evaluated as described below.

[0529] Resist Pattern Evaluation

[0530] The optimum exposure dose (sensitivity Eop) was the exposure dosewhich provided a 1:1 resolution at the top and bottom of a 0.18-μmline-and-space pattern. The minimum line width (μm) of a line-and-spacepattern which was ascertained separate at this dose was the resolutionof a test resist. The shape in cross section of the resolved resistpattern was examined under a scanning electron microscope. The depth offocus (DOF) was determined by offsetting the focal point and judging theresist to be satisfactory when the resist pattern shape was keptrectangular and the resist pattern film thickness was kept above 80% ofthat at accurate focusing.

[0531] The PED stability of a resist was evaluated by effectingpost-exposure bake (PEB) after 24 hours of holding from exposure at theoptimum dose and determining a variation in line width. The less thevariation, the greater is the PED stability.

[0532] The results of resist pattern evaluation are shown in Table 4.

[0533] Other Evaluation

[0534] The solubility of resist material in a solvent mixture wasexamined by visual observation and in terms of clogging upon filtration.

[0535] With respect to the applicability of a resist solution, unevencoating was visually observed. Additionally, using an opticalinterference film gage Lambda-Ace VM-3010 (Dainippon Screen Mfg. Co.,Ltd.), the thickness of a resist film on a common wafer was measured atdifferent positions, based on which a variation from the desired coatingthickness (0.6 μm) was calculated. The applicability was rated “good”when the variation was within 0.5% (that is, within 0.003 μm),“unacceptable” when the variation was within 1%, and “poor” when thevariation was more than 1%.

[0536] Storage stability was judged in terms of foreign matterprecipitation or sensitivity change with the passage of time. After theresist solution was aged for 100 days at the longest, the number ofparticles of 0.3 μm or larger per ml of the resist solution was countedby means of a particle counter KL-20A (Rion Co., Ltd.). Also, a changewith time of sensitivity (Eop) from that immediately after preparationwas determined. The storage stability was rated “good” when the numberof particles is not more than 5 or when the sensitivity change waswithin 5%, and “poor” otherwise.

[0537] Debris appearing on the developed pattern was observed under ascanning electron microscope (TDSEM) model S-7280H (Hitachi Ltd.). Theresist film was rated “good” when the number of foreign particles was upto 10 per 100 μm², “unacceptable” when from 11 to 15, and “poor” whenmore than 15.

[0538] Debris left after resist peeling was examined using a surfacescanner Surf-Scan 6220 (Tencol Instruments). A resist-coated 8-inchwafer was subjected to entire exposure rather than patterned exposure,processed in a conventional manner, and developed with a 2.38% TMAHsolution before the resist film was peeled off (only the resist film inthe exposed area was peeled). After the resist film was peeled, thewafer was examined and rated “good” when the number of foreign particlesof greater than 0.20 μm was up to 100, “unacceptable” when from 101 to150, and “poor” when more than 150.

[0539] The results are shown in Table 5. TABLE 1 Composition Example(pbw) 1 2 3 4 5 6 7 8 9 10 11 12 Polymer A 80 40 Polymer B 80 Polymer C80 Polymer D 80 Polymer E 80 Polymer F 80 Polymer G 80 Polymer H 80Polymer I 80 Polymer J 80 Polymer K 80 Polymer L 80 Polymer M Polymer NPAG1 3 3 3 2 PAG2 3 2 3 3 PAG3 3 1 3 PAG4 2 2 2 PAG5 1 1 1 2 PAG6 PAG7 11 2 2 1 1 PAG8 1 1 PAG9 Dissolution inhibitor Basic compound A 0.3 0.30.3 0.3 0.3 0.15 0.3 0.3 Basic compound B 0.15 0.3 0.3 0.3 0.3 Organicacid 0.5 0.5 0.5 derivative A Organic acid 0.5 derivative B Surfactant A0.25 0.25 0.25 0.25 0.25 0.25 Surfactant B 0.25 0.25 0.25 0.25 0.25 0.25UV absorber Solvent A 385 385 385 385 385 385 385 280 382 385 280 385Solvent B 105 105

[0540] TABLE 2 Composition Example (pbw) 13 14 15 16 17 18 19 20 21 2223 24 Polymer A 40 60 Polymer B 60 75 Polymer C 40 40 Polymer D 70 40 6040 Polymer E 40 10 Polymer F Polymer G 40 Polymer H Polymer I 10 20Polymer J Polymer K 40 Polymer L 40 20 70 Polymer M 40 20 Polymer N 80PAG1 3 2 2 2 2 PAG2 2 2 2 2 PAG3 3 3 2 PAG4 2 2 2 PAG5 1 1 2 2 PAG6 0.50.5 PAG7 1.5 1.5 1 1 1 PAG8 0.5 PAG9 1 1 1 Crosslinker A 20 Dissolution5 inhibitor Basic compound A 0.15 0.3 0.3 0.3 Basic compound B 0.3 0.150.3 0.3 0.3 0.3 0.3 0.3 0.3 Organic acid 0.5 0.5 derivative A Organicacid 0.25 derivative B Surfactant A 0.25 0.25 0.25 0.25 0.25 0.25Surfactant B 0.25 0.25 0.25 0.25 0.25 UV absorber 0.5 Solvent A 280 385385 385 280 385 385 385 280 385 280 385 Solvent B 105 105 105 105

[0541] TABLE 3 Comparative Example Composition (pbw) 1 2 3 Polymer A 8040 Polymer E 80 Polymer K 40 PAG5 PAG6 2.5 PAG7 1 PAG8 2.5 2.5 PAG9 1Dissolution inhibitor Basic compound A 0.125 Basic compound B 0.1250.125 Organic acid derivative A 0.5 Organic acid derivative B SurfactantA 0.25 0.25 Surfactant B 0 0.25 UV absorber Solvent A 385 385 385Solvent B

[0542] TABLE 4 24 hr PED DOF at dimensional Sensitivity Resolution 0.18μm Off-focus stability (mJ/cm²) (μm) Profile (μm) profile* (nm) Example1 37 0.14 rectangular 1.0 rectangular −10 Example 2 41 0.14 rectangular1.0 rectangular 10 Example 3 36 0.14 rectangular 1.0 rectangular −8Example 4 35 0.14 rectangular 1.0 rectangular −8 Example 5 31 0.16rectangular 1.1 rectangular −8 Example 6 33 0.15 rectangular 1.0rectangular −10 Example 7 32 0.14 rectangular 1.1 rectangular −8 Example8 35 0.16 rectangular 1.1 rectangular −8 Example 9 33 0.14 rectangular1.1 rectangular −10 Example 10 39 0.15 rectangular 1.1 rectangular −10Example 11 31 0.16 rectangular 1.0 rectangular −9 Example 12 35 0.15rectangular 1.1 rectangular −10 Example 13 39 0.15 rectangular 1.0rectangular 10 Example 14 31 0.14 rectangular 1.1 rectangular −8 Example15 33 0.14 rectangular 1.1 rectangular −8 Example 16 35 0.15 rectangular1.0 rectangular −8 Example 17 33 0.14 rectangular 1.1 rectangular −10Example 18 39 0.14 rectangular 1.0 rectangular −8 Example 19 31 0.15rectangular 0.8 rectangular −10 Example 20 35 0.14 rectangular 1.0rectangular −8 Example 21 39 0.15 rectangular 1.0 rectangular −8 Example22 31 0.14 rectangular 1.0 rectangular −10 Example 23 33 0.14rectangular 1.1 rectangular −10 Example 24 32 0.18 rectangular 0.8rectangular −9 Comparative 25 0.15 forward 0.8 forward −10 Example 1taper taper Comparative 32 0.15 rounded 0.8 rounded −8 Example 2 headhead Comparative 35 0.15 forward 0.8 forward −10 Example 3 taper taper

[0543] TABLE 5 100 day Debris after Debris after Dissolution Applicationstorage stability development resist peeling Example 1 good good goodgood good Example 2 good good good good good Example 3 good good goodgood good Example 4 good good good good good Example 5 good good goodgood good Example 6 good good good good good Example 7 good good goodgood good Example 8 good good good good good Example 9 good good goodgood good Example 10 good good good good good Example 11 good good goodgood good Example 12 good good good good good Example 13 good good goodgood good Example 14 good good good good good Example 15 good good goodgood good Example 16 good good good good good Example 17 good good goodgood good Example 18 good good good good good Example 19 good good goodgood good Example 20 good good good good good Example 21 good good goodgood good Example 22 good good good good good Example 23 good good goodgood good Example 24 good good good good good Comparative good good <30days poor unacceptable Example 1 (sensitivity changed) Comparative goodgood good unacceptable poor Example 2 Comparative good good good poorpoor Example 3

Examples 25-29 & Comparative Examples 4-6

[0544] Another experiment was performed by preparing resist solutionsaccording to the formulation shown in Table 6 and baking resist coatingsunder different conditions.

[0545] The resist materials were filtered through a 0.2-μm Teflon®filter, thereby giving resist solutions. The resist solutions werespin-coated onto silicon wafers having an organic antireflection film(DUV-44, Brewer Science) of 800 Å thick coated thereon, so as to give adry thickness of 0.6 μm.

[0546] The coated wafers were then baked on a hot plate at 120° C. for90 seconds. The resist films were exposed to 2/3 annular illuminationusing an excimer laser stepper NSR—S202A (Nikon Corporation, NA=0.6),then baked (PEB) at 130° C. for 90 seconds, and developed with asolution of 2.38% tetramethylammonium hydroxide in water. It wasexamined whether or not a pattern was formed. The results are shown inTable 7. TABLE 6 Comparative Composition Example Example (pbw) 25 26 2728 29 4 5 6 Polymer F 80 Polymer H 40 80 80 80 80 Polymer I 40 80 40Polymer J 40 PAG1 3 2 PAG2 3 1 PAG3 3 PAG4 3 PAG6 2 2 PAG7 2 PAG8 2Dissolution inhibitor Basic compound A 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3Basic compound B Organic acid derivative A 0.5 Organic acid derivative BSurfactant A 0.25 0.25 0.25 Surfactant B 0.25 0.25 UV absorber Solvent A385 385 385 385 385 385 385 385 Solvent B

[0547] TABLE 7 Sensitivity Resolution (mJ/cm²) (μm) Profile Example 2525 0.14 rectangular Example 26 23 0.15 rectangular Example 27 24 0.15rectangular Example 28 24 0.14 rectangular Example 29 24 0.14rectangular Comparative Example 4  19**  0.20** rounded head ComparativeExample 5  17**  0.20** rounded head Comparative Example 6  18**  0.20**rounded head

[0548] There have been described chemically amplified resistcompositions comprising a specific benzenesulfonyldiazomethanecontaining a long-chain alkoxyl group at the 2-position on its benzenering as the photoacid generator. The compositions have many advantagesincluding improved resolution, improved focus latitude, minimized linewidth variation or shape degradation even on long-term PED, thermalstability, minimized debris left after coating, development and peeling,and improved pattern profile after development. Because of highresolution, the compositions are suited for microfabrication, especiallyby deep UV lithography.

[0549] Japanese Patent Application No. 2003-035077 is incorporatedherein by reference.

[0550] Although some preferred embodiments have been described, manymodifications and variations may be made thereto in light of the aboveteachings. It is therefore to be understood that the invention may bepracticed otherwise than as specifically described without departingfrom the scope of the appended claims.

1. A sulfonyldiazomethane compound having the following general formula (1):

wherein R is each independently a substituted or unsubstituted straight, branched or cyclic alkyl group of 1 to 4 carbon atoms, G is SO₂ or CO, R³ is a substituted or unsubstituted straight, branched or cyclic alkyl group of 1 to 10 carbon atoms or a substituted or unsubstituted aryl group of 6 to 14 carbon atoms, p is 1 or 2, q is 0 or 1, satisfying p+q=2, m is an integer of 3 to 11, and k is an integer of 0 to 4, with the proviso that in the event k is at least 1, at least one of R associated with k may bond with the R at the 4-position to form a cyclic structure with the carbon atoms on the benzene ring to which these R's are attached, and then, these two R's bond together to form an alkylene group of 3 to 4 carbon atoms.
 2. A sulfonyldiazomethane compound having the following general formula (1a):

wherein R is each independently a substituted or unsubstituted straight, branched or cyclic alkyl group of 1 to 4 carbon atoms, and m is an integer of 3 to
 11. 3. A photoacid generator for a chemical amplification type resist composition comprising the sulfonyldiazomethane compound of claim
 1. 4. A chemical amplification type resist composition comprising (A) a resin which changes its solubility in an alkaline developer under the action of an acid, and (B) the sulfonyldiazomethane compound of claim 1 which generates an acid upon exposure to radiation.
 5. A chemical amplification type resist composition comprising (A) a resin which changes its solubility in an alkaline developer under the action of an acid, (B) the sulfonyldiazomethane compound of claim 1 which generates an acid upon exposure to radiation, and (C) a compound capable of generating an acid upon exposure to radiation, other than component (B).
 6. The resist composition of claim 4 wherein the resin (A) has such substituent groups having C—O—C linkages that the solubility in an alkaline developer changes as a result of scission of the C—O—C linkages under the action of an acid.
 7. The resist composition of claim 6 wherein the resin (A) is a polymer containing phenolic hydroxyl groups in which hydrogen atoms of the phenolic hydroxyl groups are substituted with acid labile groups of one or more types in a proportion of more than 0 molt to 80 molt on the average of the entire hydrogen atoms of the phenolic hydroxyl groups, the polymer having a weight average molecular weight of 3,000 to 100,000.
 8. The resist composition of claim 7 wherein the resin (A) is a polymer comprising recurring units of the following general formula (2a):

wherein R⁴ is hydrogen or methyl, R⁵ is a straight, branched or cyclic alkyl group of 1 to 8 carbon atoms, x is 0 or a positive integer, y is a positive integer, satisfying x+y≦5, R⁶ is an acid labile group, S and T are positive integers, satisfying 0<T/(S+T)≦0.8, wherein the polymer contains units in which hydrogen atoms of phenolic hydroxyl groups are partially substituted with acid labile groups of one or more types, a proportion of the acid labile group-bearing units is on the average from more than 0 mol % to 80 molt based on the entire polymer, and the polymer has a weight average molecular weight of 3,000 to 100,000.
 9. The resist composition of claim 6 wherein the resin (A) is a polymer comprising recurring units of the following general formula (2a′):

wherein R⁴ is hydrogen or methyl, R⁵ is a straight, branched or cyclic alkyl group of 1 to 8 carbon atoms, R⁶ is an acid labile group, R^(6a) is hydrogen or an acid labile group, at least some of R^(6a) being acid labile groups, x is 0 or a positive integer, y is a positive integer, satisfying x+y≦5, M and N are positive integers, L is 0 or a positive integer, satisfying 0<N/(M+N+L)≦0.5 and 0<(N+L)/(M+N+L)≦0.8, wherein the polymer contains on the average from more than 0 mol % to 50 mol % of those units derived from acrylate and methacrylate, and also contains on the average from more than 0 mol % to 80 mol % of acid labile group-bearing units, based on the entire polymer, and the polymer has a weight average molecular weight of 3,000 to 100,000.
 10. The resist composition of claim 6 wherein the resin (A) is a polymer comprising recurring units of the following general formula (2a″):

wherein R⁴ is hydrogen or methyl, R⁵ is a straight, branched or cyclic alkyl group of 1 to 8 carbon atoms, R⁶ is an acid labile group, R^(6a) is hydrogen or an acid labile group, at least some of R^(6a) being acid labile groups, x is 0 or a positive integer, y is a positive integer, satisfying x+y≦5, yy is 0 or a positive integer, satisfying x+yy≦5, A and B are positive integers, C, D and E each are 0 or a positive integer, satisfying 0<(B+E)/(A+B+C+D+E)≦0.5 and 0<(C+D+E)/(A+B+C+D+E)≦0.8, wherein the polymer contains on the average from more than 0 mol % to 50 mol % of those units derived from indene and/or substituted indene, and also contains on the average from more than 0 mol % to 80 mol % of acid labile group-bearing units, based on the entire polymer, and the polymer has a weight average molecular weight of 3,000 to 100,000.
 11. The resist composition of claim 7 wherein the acid labile group is selected from the class consisting of groups of the following general formulae (4) to (7), tertiary alkyl groups of 4 to 20 carbon atoms, trialkylsilyl groups whose alkyl moieties each have 1 to 6 carbon atoms, oxoalkyl groups of 4 to 20 carbon atoms, and aryl-substituted alkyl groups of 7 to 20 carbon atoms,

wherein R¹⁰ and R¹¹ each are hydrogen or a straight, branched or cyclic alkyl having 1 to 18 carbon atoms, and R¹² is a monovalent hydrocarbon group of 1 to 18 carbon atoms which may contain a heteroatom, a pair of R¹⁰ and R¹¹, R¹⁰ and R¹², or R¹¹ and R¹² may together form a ring, with the proviso that R¹⁰, R¹¹, and R¹² each are a straight or branched alkylene of 1 to 18 carbon atoms when they form a ring, R¹³ is a tertiary alkyl group of 4 to 20 carbon atoms, a trialkysilyl group in which each of the alkyls has 1 to 6 carbon atoms, an oxoalkyl group of 4 to 20 carbon atoms, or a group of the formula (4), z is an integer of 0 to 6, R¹⁴ is a straight, branched or cyclic alkyl group of 1 to 8 carbon atoms or an aryl group of 6 to 20 carbon atoms which may be substituted, h is 0 or 1, i is 0, 1, 2 or 3, satisfying 2h+i=2 or 3, R¹⁵ is a straight, branched or cyclic alkyl group of 1 to 8 carbon atoms or an aryl group of 6 to 20 carbon atoms which may be substituted, R¹⁶ to R²⁵ are each independently hydrogen or a monovalent hydrocarbon group of 1 to 15 carbon atoms which may contain a heteroatom, any two of R¹⁶ to R²⁵, taken together, may form a ring, each of the ring-forming two of R¹⁶ to R²⁵ is a divalent hydrocarbon group of 1 to 15 carbon atoms which may contain a heteroatom, or two of R¹⁶ to R²⁵ which are attached to adjoining carbon atoms may bond together directly to form a double bond.
 12. The resist composition of claim 4 further comprising (D) a basic compound.
 13. The resist composition of claim 4 further comprising (E) an organic acid derivative.
 14. The resist composition of claim 4 further comprising as an organic solvent a propylene glycol alkyl ether acetate, an alkyl lactate or a mixture thereof.
 15. A process for forming a pattern, comprising the steps of: applying the resist composition of claim 4 onto a substrate to form a coating, heat treating the coating and exposing the coating to high energy radiation with a wavelength of up to 300 nm or electron beam through a photomask, optionally heat treating the exposed coating, and developing the coating with a developer. 